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 re-producibly 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 I~V for source impedances up to 1012 ~ using films about 1 i~m in thickness. Measure-ments were performed on numerous electrodeposited materials: CdTe, CdS, CdSe, and Hg=Cd(l.=)Te. Argon annealed elec-trodeposited CdTe was found to be consistently p-type, with resistivity values typically 106-107 9~- cmp-- ~ n conversion of CdTe was achieved by diffusion of Cd at high temperature. Hg=Cdc~_=)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 101 ~ cm ~ and 1014-1016 cm-~, respectively. The electrical characterization f electrodeposited thin film materials by Hall effect or resistance measurements is complicated by the fact that the sample must be removed from the conducting substrate before measurement. Previ