The physical properties of thin nanocrystalline cerium oxide films have been studied with the purpose
of their application as a functional material of different microelectronic transducers for biosensors: highperformance
photoresistors and photodiodes for bioluminescence registration, ion-selective field-effect
transistors (ISFET) and MOS-varactors indicating the pH changes as a result of biochemical processes.
The effect of technological factors on the photoelectrical, optical, temperature and electrophysical properties
of cerium oxide films has been studied. We established the technological conditions which allow to obtain
СеОх-films with desired functional characteristics. On the basis of the synthesized nanocrystalline
СеОх-films obtained by the "explosive evaporation" method we developed new types of photodetectors for
registration of bioluminescent signal (photoresistors and photodiodes) with enhanced photosensitivity (310-
330 mA/lm∙V) in the visible range. Application of cerium oxide based photoresistors in the bioluminometers
instead of photomultiplier tubes and avalanche photodiodes allows to significantly reduce the cost of bioluminometer
and increase its sensitivity when measuring at alternating signal.
On the basis of nanocrystalline СеОх-films obtained by the "metallic mirrors oxidation" method we developed
potentiometric biosensory transducers (ion-selective field-effect transistors and MOS-varactors)
with CeOx as gate dielectric. It yields higher sensitivity and stability as compared to the use of the SiO2
and Si3N4 films.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3496

Maksimchuk, N.

Electronic Sumy State University Institutional Repository

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 1 No 2, 02NNBM28(3pp) (2012)   2304-1862/2012/1(2)02NNBM28(3) 02NNBM28-1  2012 Sumy State University Nanocrystalline Cerium Oxide Films for Microelectronic Biosensor Transducers   N.V. Maksimchuk*  National Technical University of Ukraine «Kiev Polytechnic Institute», 37, pr. Peremogy, 03056 Kiev, Ukraine  (Received 27 June 2012; published online 08 August 2012)  The physical properties of thin nanocrystalline cerium oxide films have been studied with the purpose of their application as a functional material of different microelectronic transducers for biosensors: high-performance photoresistors and photodiodes for bioluminescence registration, ion-selective field-effect transistors (ISFET) and MOS-varactors indicating the pH changes as a result of biochemical processes. The effect of technological factors on the photoelectrical, optical, temperature and electrophysical proper-ties of cerium oxide films has been studied. We established the technological conditions which allow to ob-tain СеОх-films with desired functional characteristics. On the basis of the synthesized nanocrystalline СеОх-films obtained by the "explosive evaporation" method we developed new types of photodetectors for registration of bioluminescent signal (photoresistors and photodiodes) with enhanced photosensitivity (310-330 mA/lm∙V) in the visible range. Application of cerium oxide based photoresistors in the bioluminometers instead of photomultiplier tubes and avalanche photodiodes allows to significantly reduce the cost of bio-luminometer and increase its sensitivity when measuring at alternating signal.  On the basis of nanocrystalline СеОх-films obtained by the "metallic mirrors oxidation" method we de-veloped potentiometric biosensory transducers (ion-selective field-effect transistors and MOS-varactors) with CeOx as gate dielectric. It yields higher sensitivity and stability as compared to the use of the SiO2 and Si3N4 films.  Keywords: Nanocrystalline cerium oxide films, СеОх, СеО2, Се2О3, Thin-film photoresistors, Photodiodes, ion-sensitive field-effect transistors, ISFET, MOS-varactors, Microelectronic biosensors.    PACS numbers: 73.61. – r, 85.30. – z, 85.60.Dw                                                             *lejanel@ukr.net 1. INTRODUCTION  On the basis of biosensors analysis [1, 2] it was found that one of the promising trends related to the modern biosensors for detection of toxic substances are bioluminescent and potentiometric methods. Biolumi-nescent methods are typically based on the measuring of changes in intensity of bioluminescence with the help of photomultiplier tubes (FMT) and avalanche photodiodes. Potentiometric biosensors determine the change in charge in the solution using ion-sensitive bulk electrodes. To reduce the size of biosensors, sim-plify the application of biological membrane on the transducers surface and to save expensive biological materials the bulk biosensor transducers should be replaced with the film ones. Thus the tasks of finding new sensitive materials, its investigation and the de-velopment of film transducers of biosignals with in-creased sensitivity, stability and reduced cost are of urgent interest. The aim of this work is to obtain and study the physical properties of cerium oxide films to create effective biosensor transducers.  2. FABRICATION AND EXPERIMENTAL TECH-NIQUES   Thin films of cerium oxide were obtained by various technological methods, depending on their application in sensors: CeOx films for photoresistors and photodi-odes by the method of vacuum flash evaporation (the “flash” method) and films of the external gate dielectric of ion-selective field-effect transistors by the technology of “metallic mirror” oxidation [1, 3].  Microstructure of the obtained CeOx films was stud-ied by scanning electron microscope JEOL JSM 6490LV (accelerating voltage of 20 kV), transmission electron microscope ПЕМ У-М (resolution of 0.21 nm, accelerat-ing voltage of 125 kV) and X-diffractometer DMAX - B Japan [4]. The structural properties of films of cerium oxide have been studied using X-ray photoelectron spectros-copy (SERIES 800 XPS, Kratos Analytical) [7]. An X-ray tube with a magnesium anode (U = 12 kV, I = 30 mA) with nonmonochromatic MgK [3]. СeOх-films surface morphology was studied by atomic force microscope NanoScope IIIa (DI, USA) us-ing the Periodic contact silicon probe with the nominal tip radius of  5-10 nm. Electrophysical properties of the structures based on the cerium oxide films were studied by the I-V char-acteristics [5], the study of optical and photoelectric properties - with the help of absorption and transmis-sion spectra, spectral photosensitivity and lux-ampere characteristics. The method of high-frequency C-V characteristics was used to study the cerium oxide film/single-crystal silicon interface [4].  3. CERIUM OXIDE FILM AS AN ACTIVE MATE-RIAL OF MICROELECTRONIC TRANSDUC-ERS  The problems of using of the photoelectron multipli-ers and avalanche photodiodes in the bioluminescent sensors, and also ion-selective field-effect transistors and MOS-varactors in potentiometric sensor transducers have been analyzed. In particular these are limited dy-namic range, high cost, high-voltage power of the FMT; problems with the supply voltage stabilization, probabil- N.V. MAKSIMCHUK PROC. NAP 1, 02NNBM28 (2012)   02NNBM28-2 ity of uncontrolled breakdown, low sensitivity to the short-wave boiluminescent radiation of avalanche pho-todiodes. As for the drawbacks of the potentiometric transducers based on the ion-sensitive MOS-varactors and ISFET with SiO2, Si3N4 and Ta2O5 gate dielectrics it is the lack of sensitivity and instability of the informa-tive signal due to mobile charges in the dielectric film and charge states at the oxide-semiconductor interface. To eliminate the drawbacks of luminescent biosen-sors we decided to develop a new type of photodetectors of the luminescent signal – highly sensitive, microminia-ture, stable, low-voltage and low-cost photoresistors and photodiodes based on cerium oxide films. To improve the characteristics of potentiometric MOS-sensors we followed a fundamentally new way – application of a new material as gate dielectric. The re-quirements for such material are following: close to the silicon crystal lattice parameters and hence the minimal number of charge states at the insulator-semiconductor interface, increased value of the dielectric permittivity, the highest possible number of pH-sensitive centers at the dielectric surface, thermal and chemical stability and biocompatibility. To meet the above requirements we proposed to use cerium oxide films as a functional mate-rial of the microelectronic sensor transducers (thin-film photoresistors, photodiodes, MOS-varactors and ISFET) because of the favorable combination of optical and elec-trical properties of cerium oxide. It was determined that properties of cerium oxide films and their quantitative relationships with the technological parameters (especially for their use as the active material for the sensor transducers) are studied insufficiently. On this basis it has been tasked to carry out a comprehensive study of formation of cerium oxide films with the desired functional properties for the cre-ation of microelectronic biosensors. Structural research of cerium oxide films has shown that at low substrate temperatures (Ts = 175 0C) cerium oxide films with nanocrystals in amorphous matrix are formed. The amorphous phase is represented by Ce2O3, while nanocrystalline – by CeO2 with face-centered cu-bic crystal lattice. At higher substrate temperatures Ts the “explosive evaporation” method gave nanocrystal-line films of CeO2 with the CaF2 structural type with no amorphous phase in it. Besides, such CeOx films ob-tained at 200 0C and 3000C had different grain size (close to 24 nm and 27 nm respectively), different shape of grains, and different preferred orientation. It was revealed that increasing of the substrate tem-perature from 175 to 200 0C is accompanied by the growth in photosensitivity, electrical conductivity, coeffi-cient of absorption in the short-wave visible range, reduc-tion of temperature coefficient of resistance and decreas-ing of charge states density at the film-substrate inter-face. This is caused by the transition from amorphous to nanocrystalline phase and also by changes in film compo-sition (from two-phase Ce2O3 and CeO2 to single-phase CeO2) of the cerium oxide films produced by the "explosive evaporation" technology. Further increase of the substrate temperature up to 250-300 C leads to dete-rioration of the above properties due to the changes in the morphology and phase composition of the CeOx films. As the bioluminescent methods are usually used at 450-600 nm of wavelengths, the research of the photo-sensitivity of the photoresistors and photodiodes based on cerium oxide films was carried out in this wavelength range. Thus for the photoresistors with CeOx films de-posited on SiO2/Si substrate a linear dependence of pho-tocurrent density of luminous flux was observed unlike to this dependence for Si3N4/Si substrate. The research of the spectral photosensitivity of the CeOx film photore-sistors in the spectral wavelengths range 200-800 nm, has shown that maximum photosensitivity is observed in the range of 450-550 nm, which is typical for biolumines-cent radiation. It was experimentally determined that the best char-acteristics for the creation of photodetectors of biolumi-nescent signal had the cerium oxide films deposited by explosive evaporation at substrate temperature of 200 0C. These technological conditions promote for-mation of nanocrystalline CeO2 films with a minimum number of the recombination centers (the value of the surface states density at the film-substrate interface Nss on the level of 7∙1010 sm-2∙eV-1) and a maximum value of the absorption coefficient (~ 104  sm-1), which also ex-plains the increased photosensitivity (3-3,3 mA/lm). Based on the synthesized thin nanocrystalline ceri-um oxide films we developed new types of photodetec-tors for the bioluminescent signal registration (photo-resistors and photodiodes) which have an enhanced photosensitivity value of 310-330 mA/lm∙V and have no typical deficiencies of the photoelectron multipliers and avalanche photodiodes (high cost, high-voltage power of FEM and problems of stabilization of the supply volt-age, probability of uncontrolled breakdown, low sensi-tivity to short-wave boiluminescent radiation of the avalanche photodiodes). Based on results of the research of the high-frequency C-V characteristics of MOS structures with the CeOx films obtained in different technological condi-tions it was determined that for the manufacture of ion-sensitive potentiometric biosensor transducers it is ad-visable to use a low temperature technology of metallic mirrors oxidation at the Ts  = 160 0C. In this case the highest value of dielectric permittivity (ε = 15) and of the capacitance overlap coefficient (13), the minimum value of density of surface states at the insulator-semiconductor interface (Nss = 6.8·1010 cm-2·eV-1), and also the absence of mobile charges are achieved. This enables the raise of sensitivity and stability of potenti-ometric biosensor transducers with the CeOx gate dielec-tric (ion-selective field-effect transistors and MOS varac-tors) compared to their counterparts on the basis of SiO2 and Si3N4. As a result, the pH-sensitivity of the ISFET with CeOx dielectric has risen by almost 10% compared to SiO2-Si3N4 and has reached the value of 58 mV/pH, which is close to the maximum possible sensitivity to the semiconductor-insulator-solution structure - 59.2 mV/pH. In addition, the drain current pH sensitivity of ISFET with CeOx dielectric has risen compared to SiO2-Si3N4 more than twice. Taking into account the high chemical stability of CeO2 and simplicity of the dielectric films obtaining, cerium dioxide can be considered very promising for use as ion-sensitive material in ISFET – a basic element in the creation of the biosensors for various purposes. On the basis of the efficient photodetectors developed  NANOCRYSTALLINE CERIUM OXIDE FILMS FOR MICROELECTRONIC… PROC. NAP 1, 02NNBM28 (2012)   02NNBM28-3 in this work a new type of bioluminescent sensor – a portable electronic biolumenometric device for the detec-tion of toxic substances – was developed and studied. The application of semiconductor photoresistors based on cerium oxide films in biolumenometric device instead of photoelectron multipliers and avalanche photodiodes allows to reduce the cost of biolumenometers and raise its sensitivity due to the extended sensitive surface area and highly sensitive bridge circuits using AC.  4. CONCLUSIONS  An urgent scientific problem of synthesis of the nanostructured cerium oxide films with the desired physical properties for the creation of highly efficient biosensors including multiparametric ones has been solved. Microelectronic transducers based on cerium oxide films developed in this work can be the basis for the creation of affordable, portable, highly sensitive and reliable biosensors for environmental monitoring, investigation of the effect of toxic agents on various chemical and biological processes and for other purpos-es, – instead of a costly, cumbersome and sophisticated analytical equipment used today.  AKNOWLEDGEMENTS  Author is grateful to the M.G. Dusheiko and  Yu.V. Yasievich for the providing samples of vacuum condensates.    REFERENCES  1. A.N. Shmyreva, N.V. Maksymchuk, J. Electronics and Communications No1, 5 (2007). (In Russian) 2. N.V/ Maksymchuk J. Nanosystems, nanomaterials and nanotechnology 7, No3, 813 (2009). (In Russian) 3. A.N. Shmyryeva, A.V. Borisov, N.V. Maksimchuk, J. Nan-otechnologies in Russia 5 No5-6, 382 (2010). 4. N.V. Maksymchuk, AN Shmyreva, A. Borisov, J. Techno-logy and construction of electronic equipment No5-6, 54 (2010). (In Russian) 5. A.V. Borisov, A.N. Shmyreva, N.V. Maksymchuk J. Nano-systems, nanomaterials and nanotechnology 7 No1, 245 (2009). (In Russian)  

Nanocrystalline Cerium Oxide Films for Microelectronic Biosensor Transducers

SocioEconomic Challenges Journal (Sumy State University)

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE NANOMATERIALS: APPLICATIONS AND PROPERTIES 
Vol. 1 No 2, 02NNBM28(3pp) (2012) 
 
 
2304-1862/2012/1(2)02NNBM28(3) 02NNBM28-1  2012 Sumy State University 
Nanocrystalline Cerium Oxide Films for Microelectronic Biosensor Transducers  
 
N.V. Maksimchuk* 
 
National Technical University of Ukraine «Kiev Polytechnic Institute», 37, pr. Peremogy, 03056 Kiev, Ukraine 
 
(Received 27 June 2012; published online 08 August 2012) 
 
The physical properties of thin nanocrystalline cerium oxide films have been studied with the purpose 
of their application as a functional material of different microelectronic transducers for biosensors: high-
performance photoresistors and photodiodes for bioluminescence registration, ion-selective field-effect 
transistors (ISFET) and MOS-varactors indicating the pH changes as a result of biochemical processes. 
The effect of technological factors on the photoelectrical, optical, temperature and electrophysical proper-
ties of cerium oxide films has been studied. We established the technological conditions which allow to ob-
tain СеОх-films with desired functional characteristics. On the basis of the synthesized nanocrystalline 
СеОх-films obtained by the "explosive evaporation" method we developed new types of photodetectors for 
registration of bioluminescent signal (photoresistors and photodiodes) with enhanced photosensitivity (310-
330 mA/lm∙V) in the visible range. Application of cerium oxide based photoresistors in the bioluminometers 
instead of photomultiplier tubes and avalanche photodiodes allows to significantly reduce the cost of bio-
luminometer and increase its sensitivity when measuring at alternating signal. 
 On the basis of nanocrystalline СеОх-films obtained by the "metallic mirrors oxidation" method we de-
veloped potentiometric biosensory transducers (ion-selective field-effect transistors and MOS-varactors) 
with CeOx as gate dielectric. It yields higher sensitivity and stability as compared to the use of the SiO2 
and Si3N4 films. 
 
Keywords: Nanocrystalline cerium oxide films, СеОх, СеО2, Се2О3, Thin-film photoresistors, Photodiodes, 
ion-sensitive field-effect transistors, ISFET, MOS-varactors, Microelectronic biosensors. 
 
  PACS numbers: 73.61. – r, 85.30. – z, 85.60.Dw 
 
 
                                                          
*lejanel@ukr.net 
1. INTRODUCTION 
 
On the basis of biosensors analysis [1, 2] it was 
found that one of the promising trends related to the 
modern biosensors for detection of toxic substances are 
bioluminescent and potentiometric methods. Biolumi-
nescent methods are typically based on the measuring 
of changes in intensity of bioluminescence with the 
help of photomultiplier tubes (FMT) and avalanche 
photodiodes. Potentiometric biosensors determine the 
change in charge in the solution using ion-sensitive 
bulk electrodes. To reduce the size of biosensors, sim-
plify the application of biological membrane on the 
transducers surface and to save expensive biological 
materials the bulk biosensor transducers should be 
replaced with the film ones. Thus the tasks of finding 
new sensitive materials, its investigation and the de-
velopment of film transducers of biosignals with in-
creased sensitivity, stability and reduced cost are of 
urgent interest. The aim of this work is to obtain and 
study the physical properties of cerium oxide films to 
create effective biosensor transducers. 
 
2. FABRICATION AND EXPERIMENTAL TECH-
NIQUES  
 
Thin films of cerium oxide were obtained by various 
technological methods, depending on their application 
in sensors: CeOx films for photoresistors and photodi-
odes by the method of vacuum flash evaporation (the 
“flash” method) and films of the external gate dielectric 
of ion-selective field-effect transistors by the technology 
of “metallic mirror” oxidation [1, 3].  
Microstructure of the obtained CeOx films was stud-
ied by scanning electron microscope JEOL JSM 6490LV 
(accelerating voltage of 20 kV), transmission electron 
microscope ПЕМ У-М (resolution of 0.21 nm, accelerat-
ing voltage of 125 kV) and X-diffractometer DMAX - B 
Japan [4]. 
The structural properties of films of cerium oxide 
have been studied using X-ray photoelectron spectros-
copy (SERIES 800 XPS, Kratos Analytical) [7]. An X-
ray tube with a magnesium anode (U = 12 kV, I = 
30 mA) with nonmonochromatic MgK [3]. 
СeOх-films surface morphology was studied by 
atomic force microscope NanoScope IIIa (DI, USA) us-
ing the Periodic contact silicon probe with the nominal 
tip radius of  5-10 nm. 
Electrophysical properties of the structures based 
on the cerium oxide films were studied by the I-V char-
acteristics [5], the study of optical and photoelectric 
properties - with the help of absorption and transmis-
sion spectra, spectral photosensitivity and lux-ampere 
characteristics. The method of high-frequency C-V 
characteristics was used to study the cerium oxide 
film/single-crystal silicon interface [4]. 
 
3. CERIUM OXIDE FILM AS AN ACTIVE MATE-
RIAL OF MICROELECTRONIC TRANSDUC-
ERS 
 
The problems of using of the photoelectron multipli-
ers and avalanche photodiodes in the bioluminescent 
sensors, and also ion-selective field-effect transistors and 
MOS-varactors in potentiometric sensor transducers 
have been analyzed. In particular these are limited dy-
namic range, high cost, high-voltage power of the FMT; 
problems with the supply voltage stabilization, probabil-
 N.V. MAKSIMCHUK PROC. NAP 1, 02NNBM28 (2012) 
 
 
02NNBM28-2 
ity of uncontrolled breakdown, low sensitivity to the 
short-wave boiluminescent radiation of avalanche pho-
todiodes. As for the drawbacks of the potentiometric 
transducers based on the ion-sensitive MOS-varactors 
and ISFET with SiO2, Si3N4 and Ta2O5 gate dielectrics it 
is the lack of sensitivity and instability of the informa-
tive signal due to mobile charges in the dielectric film 
and charge states at the oxide-semiconductor interface. 
To eliminate the drawbacks of luminescent biosen-
sors we decided to develop a new type of photodetectors 
of the luminescent signal – highly sensitive, microminia-
ture, stable, low-voltage and low-cost photoresistors and 
photodiodes based on cerium oxide films. 
To improve the characteristics of potentiometric 
MOS-sensors we followed a fundamentally new way – 
application of a new material as gate dielectric. The re-
quirements for such material are following: close to the 
silicon crystal lattice parameters and hence the minimal 
number of charge states at the insulator-semiconductor 
interface, increased value of the dielectric permittivity, 
the highest possible number of pH-sensitive centers at 
the dielectric surface, thermal and chemical stability and 
biocompatibility. To meet the above requirements we 
proposed to use cerium oxide films as a functional mate-
rial of the microelectronic sensor transducers (thin-film 
photoresistors, photodiodes, MOS-varactors and ISFET) 
because of the favorable combination of optical and elec-
trical properties of cerium oxide. 
It was determined that properties of cerium oxide 
films and their quantitative relationships with the 
technological parameters (especially for their use as the 
active material for the sensor transducers) are studied 
insufficiently. On this basis it has been tasked to carry 
out a comprehensive study of formation of cerium oxide 
films with the desired functional properties for the cre-
ation of microelectronic biosensors. 
Structural research of cerium oxide films has shown 
that at low substrate temperatures (Ts = 175 0C) cerium 
oxide films with nanocrystals in amorphous matrix are 
formed. The amorphous phase is represented by Ce2O3, 
while nanocrystalline – by CeO2 with face-centered cu-
bic crystal lattice. At higher substrate temperatures Ts 
the “explosive evaporation” method gave nanocrystal-
line films of CeO2 with the CaF2 structural type with no 
amorphous phase in it. Besides, such CeOx films ob-
tained at 200 0C and 3000C had different grain size 
(close to 24 nm and 27 nm respectively), different shape 
of grains, and different preferred orientation. 
It was revealed that increasing of the substrate tem-
perature from 175 to 200 0C is accompanied by the 
growth in photosensitivity, electrical conductivity, coeffi-
cient of absorption in the short-wave visible range, reduc-
tion of temperature coefficient of resistance and decreas-
ing of charge states density at the film-substrate inter-
face. This is caused by the transition from amorphous to 
nanocrystalline phase and also by changes in film compo-
sition (from two-phase Ce2O3 and CeO2 to single-phase 
CeO2) of the cerium oxide films produced by the 
"explosive evaporation" technology. Further increase of 
the substrate temperature up to 250-300 C leads to dete-
rioration of the above properties due to the changes in the 
morphology and phase composition of the CeOx films. 
As the bioluminescent methods are usually used at 
450-600 nm of wavelengths, the research of the photo-
sensitivity of the photoresistors and photodiodes based 
on cerium oxide films was carried out in this wavelength 
range. Thus for the photoresistors with CeOx films de-
posited on SiO2/Si substrate a linear dependence of pho-
tocurrent density of luminous flux was observed unlike 
to this dependence for Si3N4/Si substrate. The research 
of the spectral photosensitivity of the CeOx film photore-
sistors in the spectral wavelengths range 200-800 nm, 
has shown that maximum photosensitivity is observed in 
the range of 450-550 nm, which is typical for biolumines-
cent radiation. 
It was experimentally determined that the best char-
acteristics for the creation of photodetectors of biolumi-
nescent signal had the cerium oxide films deposited by 
explosive evaporation at substrate temperature of 
200 0C. These technological conditions promote for-
mation of nanocrystalline CeO2 films with a minimum 
number of the recombination centers (the value of the 
surface states density at the film-substrate interface Nss 
on the level of 7∙1010 sm-2∙eV-1) and a maximum value of 
the absorption coefficient (~ 104  sm-1), which also ex-
plains the increased photosensitivity (3-3,3 mA/lm). 
Based on the synthesized thin nanocrystalline ceri-
um oxide films we developed new types of photodetec-
tors for the bioluminescent signal registration (photo-
resistors and photodiodes) which have an enhanced 
photosensitivity value of 310-330 mA/lm∙V and have no 
typical deficiencies of the photoelectron multipliers and 
avalanche photodiodes (high cost, high-voltage power of 
FEM and problems of stabilization of the supply volt-
age, probability of uncontrolled breakdown, low sensi-
tivity to short-wave boiluminescent radiation of the 
avalanche photodiodes). 
Based on results of the research of the high-
frequency C-V characteristics of MOS structures with 
the CeOx films obtained in different technological condi-
tions it was determined that for the manufacture of ion-
sensitive potentiometric biosensor transducers it is ad-
visable to use a low temperature technology of metallic 
mirrors oxidation at the Ts  = 160 0C. In this case the 
highest value of dielectric permittivity (ε = 15) and of the 
capacitance overlap coefficient (13), the minimum value 
of density of surface states at the insulator-
semiconductor interface (Nss = 6.8·1010 cm-2·eV-1), and 
also the absence of mobile charges are achieved. This 
enables the raise of sensitivity and stability of potenti-
ometric biosensor transducers with the CeOx gate dielec-
tric (ion-selective field-effect transistors and MOS varac-
tors) compared to their counterparts on the basis of SiO2 
and Si3N4. As a result, the pH-sensitivity of the ISFET 
with CeOx dielectric has risen by almost 10% compared 
to SiO2-Si3N4 and has reached the value of 58 mV/pH, 
which is close to the maximum possible sensitivity to the 
semiconductor-insulator-solution structure - 59.2 
mV/pH. In addition, the drain current pH sensitivity of 
ISFET with CeOx dielectric has risen compared to SiO2-
Si3N4 more than twice. 
Taking into account the high chemical stability of 
CeO2 and simplicity of the dielectric films obtaining, 
cerium dioxide can be considered very promising for use 
as ion-sensitive material in ISFET – a basic element in 
the creation of the biosensors for various purposes. 
On the basis of the efficient photodetectors developed 
 NANOCRYSTALLINE CERIUM OXIDE FILMS FOR MICROELECTRONIC… PROC. NAP 1, 02NNBM28 (2012) 
 
 
02NNBM28-3 
in this work a new type of bioluminescent sensor – a 
portable electronic biolumenometric device for the detec-
tion of toxic substances – was developed and studied. 
The application of semiconductor photoresistors based on 
cerium oxide films in biolumenometric device instead of 
photoelectron multipliers and avalanche photodiodes 
allows to reduce the cost of biolumenometers and raise 
its sensitivity due to the extended sensitive surface area 
and highly sensitive bridge circuits using AC. 
 
4. CONCLUSIONS 
 
An urgent scientific problem of synthesis of the 
nanostructured cerium oxide films with the desired 
physical properties for the creation of highly efficient 
biosensors including multiparametric ones has been 
solved. Microelectronic transducers based on cerium 
oxide films developed in this work can be the basis for 
the creation of affordable, portable, highly sensitive 
and reliable biosensors for environmental monitoring, 
investigation of the effect of toxic agents on various 
chemical and biological processes and for other purpos-
es, – instead of a costly, cumbersome and sophisticated 
analytical equipment used today. 
 
AKNOWLEDGEMENTS 
 
Author is grateful to the M.G. Dusheiko and  
Yu.V. Yasievich for the providing samples of vacuum 
condensates. 
 
 
 
REFERENCES 
 
1. A.N. Shmyreva, N.V. Maksymchuk, J. Electronics and 
Communications No1, 5 (2007). (In Russian) 
2. N.V/ Maksymchuk J. Nanosystems, nanomaterials and 
nanotechnology 7, No3, 813 (2009). (In Russian) 
3. A.N. Shmyryeva, A.V. Borisov, N.V. Maksimchuk, J. Nan-
otechnologies in Russia 5 No5-6, 382 (2010). 
4. N.V. Maksymchuk, AN Shmyreva, A. Borisov, J. Techno-
logy and construction of electronic equipment No5-6, 54 
(2010). (In Russian) 
5. A.V. Borisov, A.N. Shmyreva, N.V. Maksymchuk J. Nano-
systems, nanomaterials and nanotechnology 7 No1, 245 
(2009). (In Russian) 
 


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Nanocrystalline Cerium Oxide Films for Microelectronic Biosensor Transducers

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