Propiedades eléctricas de películas delgadas de CdS producidas por pulverización R.F

Tesis _ Universidad Complutense de Madrid, Facultad de Ciencias Físicas,Departamento de Electricidad y Electrónica.Depto. de Estructura de la Materia, Física Térmica y ElectrónicaFac. de Ciencias FísicasTRUEProQuestpu

Characterization of polycrystalline Cu(In,Ga)Te-2 thin films prepared by pulsed laser deposition

Thin films of the chalcopyrite compound CuGaxIn1-xTe2 (0 less than or equal toX less than or equal to1) have been prepared by pulsed laser deposition (PLD) of prereacted material onto glass substrates. The structural and optical properties of these films have been investigated using the techniques of X-ray diffraction. (XRD), energy dispersive X-ray analysis (EDX), Rutherford back scattering (RBS), transmittance. (T), reflectance (R). Electrical characterization was performed using Hall and resistivity measurements, using the Van der Pauw technique at 300 K. The composition of the laser-deposited films was found to closely match that of the target materials and the XRD showed them to be single phase with the chalcopyrite structure and a preferred orientation along the (112) plane. The spectral dependence of the refractive index n and absorption coefficient a of the Cu(In,Ga)Te-2 thin films were determined using rigorous expressions for transmission and reflection in an air/film/substrate/air multilayer system. The CuGaxIn1-xTe2 films had optical absorption coefficients of order 10(4) cm(-1) and the energy gaps observed in these films increased from 0.96 to 1.32 eV with increasing Ga content

Propiedades eléctricas de películas delgadas de CdS producidas por pulverización R.F

Tesis _ Universidad Complutense de Madrid, Facultad de Ciencias Físicas,Departamento de Electricidad y Electrónica.Depto. de Estructura de la Materia, Física Térmica y ElectrónicaFac. de Ciencias FísicasTRUEProQuestpu

Electrical characterization of Al/SiNx : H/n and p-In0.53Ga0.47As structures by deep-level transient spectroscopy and conductance transient techniques

We have analyzed the influence of the dielectric composition and the post deposition rapid thermal annealing (RTA) treatment on the electrical characteristics of electron-cyclotron-resonance plasma-deposited SiNx:H/n and p-In0.53Ga0.47As interfaces. The devices are characterized by means of capacitance-voltage (C-V), deep-level transient spectroscopy (DLTS) and conductance transient analyses. Our results show that a simple cleaning step of the semiconductor surface prior to insulator deposition, and a post deposition RTA process are sufficient to obtain good-quality structures, the n-type being better than the p-type. In both cases, we conclude that a dielectric composition of x = 1.50 seems to be the best choice, and that the most adequate RTA temperature is between 500 degreesC and 600 degreesC

C-V, DLTS and conductance transient characterization of SiNx:H/InP interface improved by N-2 remote plasma cleaning of the InP surface

Electrical characterization of Al/SiNx:H/InP structures shows that ECR nitrogen plasma cleaning of InP surfaces gives rise to a noticeable improvement in the interface quality, whereas insulator and semiconductor bulk properties are maintained at a level sufficient to be used as the gate dielectric in MIS devices. Nitrogen plasma exposure was carried out just before the SiNx plasma deposition without vacuum breaking. To obtain interface state density and to detect deep levels in the semiconductor bulk, deep level transient spectroscopy (DLTS) measurements were carried out. We have also evaluated the insulator damage density, the so-called disorder-induced gap states (DIGS), by means of conductance transient analysis. Our results show that the plasma exposure in N-2 atmospheres is a valuable and simple surface conditioning method

Laser thermal annealing effects on single crystal gallium phosphide

We have studied the laser thermal annealing (LTA) effects on single crystal GaP. The samples have been analyzed by means of Raman spectroscopy, glancing incidence x-ray diffraction (GIRXD), and transmission electron microscopy (TEM) measurements. After LTA process, the Raman spectra of samples annealed with the highest energy density show a forbidden TO vibrational mode of GaP. This result suggests the formation of crystalline domains with a different orientation in the annealed region regarding the GaP unannealed wafer. This behavior has been corroborated by GIXRD measurements. TEM images show that the LTA produces a defective layer with disoriented crystalline domains in the surface. The depth of this defective layer increases with the energy density of LTA. The lack of crystallinity after LTA processes could be related with the high bond energy value of GaP

Electrical characterization of low nitrogen content plasma deposited and rapid thermal annealed Al/SiNx:H/InP metal-insulator-semiconductor structures

The influence of the dielectric composition and post deposition rapid thermal annealing (RTA) treatments on the electrical characteristics of low nitrogen content plasma-deposited Al/SiNx:H/InP structures were analyzed. To obtain the interface state density, deep level transient spectroscopy (DLTS) measurements were carried out. We have also evaluated the insulator damage density, the so-called disorder-induced gap states (DIGS), by means of conductance transient analysis. As for the dielectric composition, both the x = 0.97 and x = 1.43 values provide interfacial state density and DIGS damage values of the same order of magnitude. In the x = 0.97 case, RTA treatments reduce the insulator damage moving it towards the interface. In the x = 1.43 case this behavior is only observed for RTA temperatures lower than 500 degreesC. So, moderate temperature (C) RTA treatments improve DIGS damage. This is an important result in terms of fabricating bi-layered metal-insulator-semiconductor (MIS) structures that not only have good-quality interfaces, but also good dielectric properties

Hydrogenated polycrystalline SiGe films and their application in Thin Film Transistors

National Congress of Materials (7. 2002. Madrid). © Sociedad Española de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas. Licencia Creative Commons 3.0 España (by-nc). Trabajo financiado por la CICYT, Proyecto MAT 99-1214.En este trabajo se ha caracterizado el proceso de hidrogenación en un plasma generado por resonancia ciclotrónica de electrones de capas de SiGe policristalino obtenidas mediante cristalización en fase sólida y el efecto de la hidrogenación en las características eléctricas de transistores de película delgada fabricados usando dicho material. Los procesos de hidrogenación se realizaron a 150 y 250 ºC, con duraciones de hasta 11 horas. Los espectros de transmitancia en infrarrojo muestran solamente las bandas de absorción características de los enlaces Si-H. Estas bandas indican que el hidrógeno se incorpora al material enlazándose principalmente con los átomos de silicio. Las medidas de reflectancia en el ultravioleta indican que se crea daño en la superficie de la muestra y que éste aumenta a medida que lo hace el contenido en Ge. Los transistores de película delgada con capa activa de SiGe policristalino muestran un fenómeno de degradación consistente en que la corriente que atraviesa el canal disminuye con el tiempo manteniendo fijas las condiciones de polarización. La hidrogenación de los transistores hace que la degradación sea cada vez más lenta a medida que aumenta el tiempo de proceso en plasma a temperatura constante.The hydrogenation of polycrystalline SiGe layers, obtained by solid phase crystallization, by an electron ciclotron resonance hydrogen plasma and the influence of this hydrogenation process on the electrical characteristics of thin film transistors fabricated using this material as active layer have been studied The hydrogenation processes were carried out at 150 and 250 degreesC for several times, Lip to 11 hours. Infrared transmission spectra of these samples show only the absorption bands corresponding to Si-H bonds, indicating that hydrogen atoms are bonded mainly to silicon atoms. Ultraviolet reflectance measurements show that the surface damage caused by the plasma exposure increases as the Ge content of the film does. The transistors fabricated using polycrystalline SiGe films as active layer show a degradation phenomenon, consisting of a progressive decrease of the drain current at constant gate and drain Has. The degradation slows down as the hydrogenation time increases at constant temperature.Depto. de Estructura de la Materia, Física Térmica y ElectrónicaFac. de Ciencias FísicasTRUECICYT of Spainpu

Pulsed Laser Melting Effects on Single Crystal Gallium Phosphide

We have investigated the pulse laser melting (PLM) effects on single crystal Gal?. The samples have been studied by means of Raman spectroscopy, glancing incidence X-ray diffraction (GIRXD), van der Pauw and Hall effect measurements. After PLM process, the Raman spectra of samples annealed with the highest energy density show a forbidden TO vibrational mode of Gal?. This suggests the formation of crystalline domains with a different orientation in the Gal? PLM region regarding to the GaP unannealed region. This behavior has been corroborated by glancing incidence x-ray diffraction measurements. A slightly increase in the sheet resistivity and a suppression of the mobility in PLM samples have been observed in all the measured temperature range. Such annealing effects are a cause of great concern for intermediate band (IB) materials formation where PLM processes are required first, to recovery the lattice crystallinity after high dose ion implantation processes and second, to avoid impurities outdiffusion when the solid solubility limit is exceeded