Thin‐Film Cadmium Mercury Telluride Prepared by Nonaqueous Electrodeposition

Abstract

Using a new electrodeposition process, thin-film cadmium mercury telluride, Cd=Hg~_=Te, with (1 -x) no greater than 0.4, was electrodeposited onto an indium tin oxide-coated glass cathode. The deposition bath contained Cd(II), Hg(II), and tri-n-butyl phosphine telluride in propylene carbonate, and its composition was shown to have a direct effect on the composition of the electrodeposited films. Film composition was determined by atomic absorption spectroscopy and by proton-induced x-ray emission. Structural analysis of the cadmium mercury telluride films was achieved by way of scanning electron microscopy and x-ray diffractometry. Crystallinity of the films was shown to increase following heat-treatment in either argon or air. The bandgaps, which were determined by measuring the optical absorption spectra of these materials, were shown to decrease with increasing (1 -x), as predicted by an empirical expression.

Electrodeposition of Semiconductors

“…MCT has also been deposited onto ITO-coated glass [146]. A bath is maintained at 95 C in a three-compartment cell with a Cd metal counter electrode and a Ag/AgCl reference electrode.…”

Formation of HgCdTe by Electrochemical Atomic Layer Epitaxy (EC-ALE)

“…The EPMA results for the two previous deposits were encouraging, as it showed that the compositions of the alloy could be varied just by changing the EC-ALE program. But, in order to find out if there was a real control over the deposit composition, a series of experiments were performed by varying the HgTe cycles in the period while keeping the same number of CdTe cycles(5) and the number of periods (20). The resulting deposits were analyzed by EPMA to determine their compositions.…”

“…Electrodeposition is a simple and less expensive method and can be used to prepare high quality MCT films. Some work has been done in the field of deposition of MCT by co-deposition [3,[15][16][17][18][19] and electrodeposition in non aqueous solutions [20,21]. There has been moderate success with these techniques as the deposited MCT is not always crystalline.…”

Electrodeposited Films of CdxHg1?xTe with Bandgap Energy in the Range 1.2-1.5 eV

“…Although a variety of methods have been used for the preparation of CMT films, electrodeposition renders itself as an attractive option due to its simplicity, low cost and potential for large-scale production. Electrodeposition from aqueous [2][3][4][5][6][7] and from non-aqueous solutions [8] and voltammetric study of electrodeposition have been reported [9]. From these reports it appears that electrodeposition yields uniform and adherent films only for compositions (0.82 < x < 1) that correspond to bandgap energies in the range 1.1-1.5 eV.…”