Charge Transport Mechanism in p--Si--n--(Si2)1--x(CdS)x Semiconductor Structures

Abstract

The paper shows that it is possible to use liquid phase epitaxy to obtain single-crystal substitutional solid solution p--Si--n--(Si2)1--x(CdS)x (0 ≤ x ≤ 0,01) on silicon substrates from Sn--Si--CdS solution melt in a palladium-purified hydrogen atmosphere. The manufacturing conditions resulting in perfect epitaxial layers with mirror surfaces exhibiting the best parameters are as follows: crystallization start temperature of 1100 °С; forced cooling rate of 1 degree/min. The epitaxial films obtained feature a thickness of 20 µm and the n conductivity type, specific resistances being 0.018 Ω·cm. Investigation results concerning charge transfer mechanisms in p--Si--n--(Si2)1--x(CdS)x structures at room temperatures show that the forward current--voltage characteristic consists of several characteristic segments, and there are various mechanisms that drive charge transfer processes. At low current densities, the increase in current is due to growing concentration of injected carriers on account of simple local centres; at high densities, it is due to recombination processes in compound complexes inside which electron exchange takes place. This fact is what proves that the structure under consideration displays better rectifying properties with increasing voltage. We determined that these epitaxial films of (Si2)1--x(CdS)x (0 ≤ х ≤ 0,01) solid solutions are promising materials for high-current rectifier diodes