Electrical properties of MIS device on CdZnTe/HgCdTe

Abstract

In this paper, we report the capacitance - voltage ( C - V) properties of metal - insulator - semiconductor ( MIS) devices on CdTe / HgCdTe by the metalorganic chemical vapor deposition (MOCVD) and CdZnTe / HgCdTe by thermal evaporation. In MOCVD, CdTe layers are directly grown on HgCdTe using the metal organic sources of DMCd and DiPTe. HgCdTe layers are converted to n - type and the carrier concentration, ND is low 10(15) cm(-3) after Hg - vacancy annealing at 260 degrees C. In thermal evaporation, CdZnTe passivation layers were deposited on HgCdTe surfaces after the surfaces were etched with 0.5 - 2.0 % bromine in methanol solution. To investigate the electrical properties of the MIS devices, the C - V measurement is conducted at 80K and 1MHz. C - V curve of MIS devices on CdTe / HgCdTe by MOCVD has shown nearly flat band condition and large hysteresis, which is inferred to result from many defects in CdTe layer induced during Hg - vacancy annealing process. A negative flat band voltage ( V-FB congruent to -2 V) and a small hysteresis have been observed for MIS devices on CdZnTe / HgCdTe by thermal evaporation. It is inferred that the negative flat band voltage results from residual Te4+ on the surface after etching with bromine in methanol solution.