REMOVAL AND PREPARATION OF ELECTRODEPOSITED SEMICONDUCTORS FOR HIGH IMPEDANCE HALL-EFFECT MEASUREMENTS

The preparation of electrodeposited semiconductors for Hall effect measurements is complicated by the fact that these materials are, by necessity, attached to highly conducting substrates. As a result, methods were developed to reproducibly remove large area samples from their conducting substrates, and suitably prepared samples were used for temperature-dependent Hall measurements and resistivity measurements. Apparatus was designed and built to routinely measure Hall voltages as low as 250-mu-V for source impedances up to 10(12) OMEGA using films about 1-mu-m in thickness. Measurements were performed on numerous electrodeposited materials: CdTe, CdS, CdSe, and HgxCd(1-x)Te. Argon annealed electrodeposited CdTe was found to be consistently p-type, with resistivity values typically 10(6)-10(7) . OMEGA . cm p --> n conversion of CdTe was achieved by diffusion of Cd at high temperature. HgxCd(1-x)Te was also p-type, but had much lower resistivity and higher carrier concentration than CdTe. CdS and CdSe were both n-type with carrier concentrations typically 10(16) cm-3 and 10(14)-10(16) cm-3, respectively.