Articles you may be interested inLow temperature catalytic formation of Sibased metal-oxide-semiconductor structure Depth profile of trapped charges in oxide layer of 6HSiC metal-oxide-semiconductor structures Electric field induced second harmonic generation spectroscopy on a metaloxidesilicon structureThe oxidation of single-crystalp-type CdTe of IIIl} orientation by thennal, wet chemical, and plasma techniques has been investigated. The C-V measurements of metal-oxide-semiconductor (MOS) structures prepared from various oxides indicate that device quality thermal oxide can be prepared by hydrogen annealing ofCdTe prior to oxidation. The thermal oxide consists mainly of Te0 2 • MOS structures prepared from oxidation of the Cd(!I1) or Te(Hl) face ofCdTe show low oxide fixed charge density (l01l/cm2) and low interface state density (1010 Icm 2 eV). MOS structures prepared from wet chemical oxide and plasma oxide have less desirable properties.

Temperature dependence of the thermal diffusivity of GaAs in the 100-305 K range measured by the pulsed photothermal displacement technique

The electrical properties of n-CdS/p-CdTe heterojunctions depend strongly on the cleanliness of the interface region. In this work, CdTe films were deposited on CdS/glass substrates by close-spaced sublimation (CSS) under various conditions. The dark current-voltage characteristics of the resulting heterojunctions were measured over a wide temperature range, and the capacitance-voltage characteristics were measured in the dark and under illumination. When the CdS surface is in situ cleaned prior to the deposition of the CdTe film, the current transport across the junction is controlled by a thermally activated process. Tunneling makes an important contribution to the interface recombination at temperatures below room temperature when the in situ cleaning of CdS is not used. The dark capacitance of CdS/CdTe heterojunctions prepared with in situ etching is essentially independent of the reverse bias due to intrinsic interface states. Under white light illumination, the 1/C 2 vs V relation is nearly linear. The CdS/CdTe heterojunctions without in situ cleaning showed different 1/C 2 vs V relations due to higher density of interface states. The in situ cleaning also has pronounced effects on the frequency dependence of dark and illuminated capacitances. Using the in situ cleaning technique, solar cells of about 1 cm2 area have achieved an AM 1.5 (global) efficiency of about 10.5%.

Al/p-CdTe Schottky barriers diodes were prepared from the Te (1̄1̄1̄) face of lightly doped p-type CdTe single crystals. The characteristics of the diodes have been found to depend strongly on the surface preparation of CdTe. The current-voltage characteristics of diodes prepared from Br2-CH3OH etched surfaces are dominated by the tunneling mechanism with high saturation current densities. The use of Br2-CH3OH etch followed by heating in hydrogen has pronounced effects on the diode quality factor and saturation current densities due to the restoration of the surface stoichiometry. The C-V measurements at 1 and 10 MHz indicate that Schottky diodes prepared from Br2-CH3OH etched and 450 °C hydrogen-annealed CdTe have a barrier height of 0.76 V and that diodes prepared from Br2-CH3OH etched or lower-temperature hydrogen-annealed CdTe show larger barrier heights. In latter cases, the barrier height appears to be controlled by the metal-semiconductor interface states. In Al/p-CdTe Schottky barriers with low interface state density, the temperature dependence of the saturation current density suggests that diffusion is the dominant mechanism of current transport, due presumably to the low carrier density in CdTe.

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