The photovaractor for optically controlled microwave circuits was designed and studied. The photovaractor module was fabricated as a planar p-i-n photodiode chip placed in a fibre optic matching receptacles. Study of C-V characteristics in the light illumination mode has shown that capacitance characteristics are strongly dependent on the light illumination power. These variations of the photovaractor diode capacitance are large enough to be used in optically controlled circuits such as oscillators, mixers and switchers

Andrievski, Vatslav F.

Baolin, Liu

Budko, Tamara O.

Chao, Chen

Chizh, Alexander L.

Gushchinskaya, Elena V.

Malyshev, Sergey A.

Romanova, Ludmila I.

Zaporozhets, Emilia V.

Biblioteka Cyfrowa Instytutu Łączności / National Institute of Telecomunications: Digital Library

Paper Photovaractor performancefor optically controlled microwave circuitsSergey A. Malyshev, Vatslav F. Andrievski, Tamara O. Budko, Chen Chao, Alexander L. Chizh,Elena V. Gushchinskaya, Liu Baolin, Ludmila I. Romanova, and Emilia V. ZaporozhetsAbstract — The photovaractor for optically controlled mi-crowave circuits was designed and studied. The photovarac-tor module was fabricated as a planar p-i-n photodiode chipplaced in a fibre optic matching receptacles. Study of C-Vcharacteristics in the light illumination mode has shown thatcapacitance characteristics are strongly dependent on the lightillumination power. These variations of the photovaractordiode capacitance are large enough to be used in opticallycontrolled circuits such as oscillators, mixers and switchers.Keywords — circuits, photovaractor, optically controlled.1. IntroductionVarious varactor diodes are extensively used in microwaveapplications, which include phase shifter, frequency mul-tiplier, mixer and nonlinear transmission-line [1 – 4]. Inrecent years the application of photonic devices for such op-tically controlled microwave circuits are discussed widelyin literature [5 – 9]. The advantages of optical control arehigh tuning speed and good isolation between controllingand microwave signals.One of optical control means is the use of junction capaci-tance variation due to optical illumination. We propose tocall such a device as the photovaractor. In this paper wereport measurements of photovaractor fabricated as a pla-nar p-i-n InP/InGaAs photodiode placed in a fibre opticmatching receptacle. Variation of the photovaractor char-acteristics due to optical illumination with different lightpower are studied.2. Photovaractor diodeThe photovaractor described in this paper is a planar p-i-nphotodiode with front illuminated p+-region and backohmic contact to n+-InP substrate. The p-i-n photodi-ode has been fabricated in n-InP/n-InGaAs/n+-InP het-erostructure which was grown on a substrate by lowpressure metal-organic vapour-phase epitaxy (LP-MOVPE).The heterostructure has been studied using electrochemi-cal C-V profiling method before making the photodetec-tor chip. Figure 1 shows the cross-section of the pla-nar InP/InGaAs p-i-n photodiode. The epitaxial layer iscomposed of 0:6 m m, 1:2  1015 cm 3 undoped n-InP toplayer, 1:5 m m, 1:2  1015 cm 3 undoped n-InGaAs absorp-tion layer, 0:5 m m undoped n-InP buffer layer on 400 m m,3 1018 cm 3 Te doped n+-InP substrate. The Hall methodmeasurement has given following majority carrier mobilityvalues in InGaAs absorption layer: 7735 cm2/Vs at 300 K,and 64084 cm2/Vs at 78 K.Fig. 1. Cross-section of the planar InP/InGaAs p-i-n photovar-actor.The p+-region was formed by local diffusion of Zn intothe wide band gap n-InP top layer. The Zn diffusion wasperformed in an open gas flow system into unpassivatedInP surface at 470ÆC [10]. The results of electrochemi-cal C-V measurements indicated that the average dopinglevel in the p+-InP layer for this diffusion conditions was7:5 1018 cm 3, and the layer thickness was 0:5 m m. SiO2films of 0:25 0:01 m m thickness were used as diffusionmask and passivative layer for the planar diode structure.These films have been made by pyrolysis of tetraethoxysi-lane at 330 350ÆC in O2/N2 flow. Ohmic contacts to p+-and n+-regions were formed using AuZn and AuGe bi-nary alloys, respectively. Contact annealing was performedat 350ÆC in H2 flow. Contact resistance for both p+- andn+-regions was 1  3  10 6 W  cm2. The diameter of thephotosensitive area was 100 m m.The photovaractor module has been fabricated as a planarp-i-n photodiode chip placed in a fibre optic matching re-ceptacle. To reduce reflection from the fibre-air, air-opticsand air-chip boundaries, a special matching medium havinga refractive index close to that of quartz fibre was used [11].3. Results and discussionMeasurements of I-V characteristics of the photovaractorhave shown that the breakdown voltage was 50 V. The val-ues of dark current were 3:5  3:7  10 9 A under 1.0 Vreverse bias, and 4:0  4:1  10 9 A under 15 V bias. Ca-14Photovaractor performance for optically controlled microwave circuitspacitance variation with bias voltage in dark condition isshown in Fig. 2. The measurements were carried out withLCG-meter at 1 MHz. One can see that with the biasvoltage variation the capacitance change is small and theratio Cmax=Cmin is equal to 2.35. Frequency measurementswere carried out using 1300 nm semiconductor laser with2.5 mW power as a source. Spectral analyser with thebandwidth from 0.4 GHz up to 3.0 GHz was used as a re-ceiver in the source-detector system. The receptacled p-i-nphotodiode module with 50 W matching resistors has thebandwidth over 1.5 GHz.Fig. 2. C-V characteristic of the photovaractor in dark condition.Figure 3 presents the response of the photovaractormodule measured in the 700  1800 nm range in biasfree conditions. The photovaractor module response is0:75 0:05 A/W at wavelength 1300 nm. It is necessaryto note that the response is not changed under reverse biasvoltage variation. This fact gives us the possibility to con-clude that the depleted region of p-i-n junction penetratesthrough the absorption InGaAs layer down to the bufferlayer and photocarriers are collected completely even inthe bias free conditions.Figure 4 shows I-V characteristics of the photovaractor un-der different optical power illumination. It can be seen thatthe photovaractor has linear response up to 750 m W opticalpower in the bias free conditions.Photovaractor’s capacitance can be strongly modified by op-tical illumination. Figure 5 shows the capacitance variationversus optical illumination power under different bias volt-ages. In the dark condition we have usual a decrease of thediode capacitance with the reverse bias voltage because thediode’s depleted region width slightly increases. The de-pleted region width decreases significantly with the opticalpower increase and this results in the increasing capaci-tance. The ratio Cmax=Cmin depends on the variation rangeof the optical power and bias voltage (Fig. 5). For example,at the bias voltage +0:1 V the capacitance changes fromFig. 3. Spectral response of the photovaractor.Fig. 4. I-V characteristics of the photovaractor under differentoptical power.Cmin = 2.75 pF up to Cmax = 69 pF under the optical powervariation from zero to 400 m W, i.e. the ratio Cmax=Cmin isequal to 25. At the bias voltage  0:4 V and optical powervariation from zero up to 750 m W the ratio Cmax=Cmin de-creases to 15. It is necessary to note that the capacitancenonlinearity increases when the optical power is increased.For example, under the bias  0:4 V and optical power vari-ation from zero up to 400 m W the ratio Cmax=Cmin is equalto 2, and it increases to 15 under the extension of opticalpower variation range up to 750 m W.Analysis of capacitance change under different conditionsgives the possibility to choose the optimum operationregime of the photovaractor. It seems that the best one is15S. A. Malyshev, V. F. Andrievski, T. O. Budko, C. Chao, A. L. Chizh, E. V. Gushchinskaya, L. Baolin, L. I. Romanova, and E. V. ZaporozhetsFig. 5. The capacitance versus optical illumination power varia-tion under different bias voltages.near bias free region because the photovaractor has widejunction capacitance variation range due to illumination, aswell as good sensitivity, frequency bandwidth and low darkcurrent.4. ConclusionsThe receptacled p-i-n photovaractor module incorporatingthe matching medium are presented. The study of C-Vcharacteristics in the light illumination mode has shownthat the capacitance characteristics are strongly dependenton the light illumination power. These junction capacitancevariations of the photovaractor diode are large enough tobe used in optically controlled microwave circuits such asoscillators, mixers and switchers.AcknowledgementsThe authors is grateful to Prof. Bogdan Galwas for hisencouraging interest and attention to this work. This workhas been completed thanks to support of the BelorussianRepublican Fund of Fundamental Investigation and NaturalScience Foundation of China.References[1] D. M. Krafcsik, S. A. Imhoff, D. E. Dawson, and A. L. Conti,“A dual-varactor analog phase shifter operating at 6–18 GHz”, IEEETrans. Microw. Theory Techn., vol. 36, no. 12, pp. 1938–1941, 1988.[2] W. C. B. Peatman, T. W. Crowe, and M. Shur, “A novelSchottky/2-DEG diode for millimeter- and submillimeter-wave mul-tiplier applications”, IEEE Electron. Dev. Lett., vol. 13, no. 1,pp. 11–13, 1992.[3] J. N. Poelker and R. S. Robertson, “A comparison of planar dopedbarrier diode performance versus Schottky diode performance ina single balanced, MIC mixer with low LO drive”, IEEE Trans.Microw. Theory Techn., vol. 43, no. 6, pp. 1241–1246, 1995.[4] M. J. W. Rodwell, M. Kamegawa, R. Yu, M. Case, E. Carman, andK. S. Giboney, “GaAs nonlinear transmission lines for picosecondpulse generation and millimeter-wave sampling”, IEEE Trans. Mi-crow. Theory Techn., vol. 39, no. 7, pp. 1194–1204, 1991.[5] Z. Szczepaniak and B. Galwas, “Optically-controlled microwavephase-shifter”, in Proc. Symp. High Perfor. Electron Dev. Mi-crow. & Optoelectron. Appl. (EDMO’99), London, U.K., Nov. 1999,pp. 290–292.[6] B. Galwas, “Photonic technology for microwave engineering”, inProc. 12th Int. Conf. Microw. & Radar (MIKON), Krakow, Poland,May 1998, vol. 4, pp. 117–135.[7] Z. Varga, G. Jaro, and B. Erdos, “Optical control of microwave filtersusing photodiodes”, in Proc. 10th MICROCOLL Conf., Budapest,Hungary, March 1999, pp. 299–302.[8] Dong-Wook Kim, Jae-Jin Lee, Young-Se Kwon, and Song-CheolHong, “Characteristics of an area-variable varactor diode”, IEEETrans. Microw. Theory Techn., vol. 44, no. 11, pp. 2053–2057, 1996.[9] C. K. Sun, C. T. Chang, R. Nguyen, and D. J. Albares, “Photovoltaicp-i-n diodes for RF control – switching applications”, IEEE Trans.Microw. Theory Techn., vol. 47, no. 10, pp. 2034–2036, 1999.[10] T. O. Budko, E. V. Gushchinskaya, Yu. S. Emelyanenko, andS. A. Malyshev, “Diffusion of zinc into an unpassivated surfaceof indium phosphide”, Phys. Stat. Sol. (a), vol. 111, pp. 451–456,1989.[11] V. F. Andrievski and S. A. Malyshev, “High speed InGaAs pho-todetector modules for fibre optic communications”, in Proc. Work-shop High Perfor. Electron Dev. Microw. & Optoelectron. Appl.(EDMO’97), London, U.K., Nov., 1997, pp. 335–339.Sergey A. Malyshev graduated from the Minsk Radio-Engineering Institute in 1970. He received the Ph.D. degreein electronic engineering from the Institute of Electronics,National Academy of Sciences of Belarus, in 1979. Since1985 he has been a head of the Laboratory of Semicon-ductor Optoelectronics. He has authored and co-authoredover 70 papers. Research work conducted by Dr. Maly-shev is devoted to experimental and theoretical investigationof physical processes in optoelectronic devices based onAIII-BV compounds, photodetectors for fiber-optic commu-nication, and their applications.e-mail: malyshev@inel.bas-net.byInstitute of ElectronicsNational Academy of Sciences of Belarus22 Lagoiski Trakt220090 Minsk, BelarusVatslav F. Andrievski graduated from the St. PetersburgElectroengineering Institute in 1983. His speciality is opto-electronic devices. From 1983 to 1991 he worked at the In-stitute of Radiomaterials and was involved in the project forstudies of GaAs switches. He also investigated the electro-physical and optical properties of GaAs, InP and InGaAs.He joined the Institute of Electronics, National Academy ofSciences of Belarus, in 1991. His main research interest is16Photovaractor performance for optically controlled microwave circuitsthe study of electrophysical properties of bulk AIII-BV ma-terials with use of photoelectrochemical method, optoelec-tronic component design and packaging. He has authoredand co-authored more than 30 papers.Institute of ElectronicsNational Academy of Sciences of Belarus22 Lagoiski Trakt220090 Minsk, BelarusTamara O. Budko worked at the Institute of Electronics,National Academy of Sciences of Belarus, from 1978, aftergraduation from Belarussian State University. Since 1998she has worked at the Institute of Radiomaterials (Minsk).Her research interests include the chemical etching andtreatment of the AIII-BV semiconductors. She has authoredand co-authored more than 20 papers.Institute of ElectronicsNational Academy of Sciences of Belarus22 Lagoiski Trakt220090 Minsk, BelarusChen Chao graduated in 1965 from the Department ofPhysics, Xiamen University, majoring in semiconductorphysics and physics of semiconductor devices with B.S. de-gree. In 1992–1993 he was researching the photoelectronicproperties and photoelectronic devices of III-V materials atthe Department of Materials and Metallurgy, Toronto Uni-versity, Canada, and the Department of Physics, Belarus-sian State University, Belarus. Chen Chao is a Professor atthe Department of Physics, Xiamen University in China. Heis engaged in scientific research on semiconductor photo-electronic properties, photoelectronic devices, OEIC and itsapplication in optical fiber communication and CATV.Department of PhysicsXiamen UniversityXiamen 361005, ChinaAlexander L. Chizh graduated with honors from the Be-larussian State University (Minsk) in June 1999 and re-ceived the degree of Bachelor of Science. Since 1999 he hasworked towards the Ph.D. thesis at the Laboratory of Semi-conductor Optoelectronics, Institute of Electronics (Minsk).His research interests are in the area of microwave photon-ics, theoretical and experimental studies of photoelectricalprocesses in multilayers heterostructures based on AIII-BVcompounds, photodetectors for fiber-optic communication,and their applications. He is the author and co-author of10 papers.Institute of ElectronicsNational Academy of Sciences of Belarus22 Lagoiski Trakt220090 Minsk, BelarusElena V. Gushchinskaya has worked at the Laboratoryof Semiconductor Optoelectronics, Institute of Electronics,National Academy of Sciences of Belarus, since 1977, aftergraduation from Minsk Radioengineering Institute. Her re-search interests include investigation of the Zn diffusion inthe AIII-BV semiconductor materials.Institute of ElectronicsNational Academy of Sciences of Belarus22 Lagoiski Trakt220090 Minsk, BelarusLiu Baolin received his B.S. degree from the Departmentof Physics, Zhongshan University in 1984, the M.S. degreefrom 13th Institute of Electronic Department in 1987, andthe Ph.D. degree from Electronical Engineering Depart-ment, Jilin University in 1993. From Oct. 1999 to Sept.2001 he worked at Venture Business Lab. of Chiba Univer-sity in Japan as a Research Scientist. He has been engagingin the research of MOCVD growth and optoelectronic de-vice for optical fiber communication and wide gap material.Liu Baolin is an Associate Professor at the Department ofPhysics, Xiamen University in China.Department of PhysicsXiamen UniversityXiamen 361005, ChinaLudmila I. Romanova has worked at the Institute of Elec-tronics, National Academy of Sciences of Belarus, since1974, after graduation from Moscow Institute of ElectronicTechniques. Since 1991 she works at the Laboratory ofSemiconductor Optoelectronics. Her research interest in-clude the forming of ohmic contacts in the optoelectronicdevices.Institute of ElectronicsNational Academy of Sciences of Belarus22 Lagoiski Trakt220090 Minsk, BelarusEmilia V. Zaporozhets graduated from the Department ofChemistry, Moscow Chemistry and Technology Institute,in 1966. She received the Ph.D. degree in chemistry in1972. She has worked at the Institute of Electronics, Na-tional Academy of Sciences of Belarus, since 1979. Herresearch interests include investigations of processes inAIII-BV semiconductor surfaces and forming the ohmiccontacts to the AIII-BV compounds.Institute of ElectronicsNational Academy of Sciences of Belarus22 Lagoiski Trakt220090 Minsk, Belarus17

Photovaractor performance for optically controlled microwave circuits, Journal of Telecommunications and Information Technology, 2002, nr 1

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Photovaractor performance for optically controlled microwave circuits, Journal of Telecommunications and Information Technology, 2002, nr 1

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