ELECTROCHEMICAL DEPOSITION OF N-ZINC MERCURY SELENIDE THIN-FILMS

Zn1-xHgxSe films with x ranging from 0.2 to 1 were prepared by electro chemical deposition from aqueous baths at 25-85 degrees C. Both bath c omposition and deposition potential were varied over a wide range. Lar ge variations of the mercury content of the films can be realized by a ppropriate choice of the deposition potential while for a given deposi tion potential the mercury content increases steeply with increasing m ercury concentration in the bath and tends towards a limiting value. T he deposition potential is therefore the chief parameter permitting a predetermined film composition to be established. For a series of film s deposited at potentials between -0.5 and -1.0 V vs. SCE, the lattice parameter a of the cubic ternary compound obtained from the X-ray dif fractograms (XRD) gives a stoichiometric factor x matching closely the mercury content (at.%) found by electron probe microanalysis (EPMA). This Hg content (at.%) can therefore be directly related to the stoich iometric factor x showing that essentially all mercury is incorporated in the single phase, Zn1-xHgxSe. The crystallinity (crystal size) imp roves with increasing x. This is accompanied by more pronounced orient ation of the crystallites in the (111) direction. HgSe is almost compl etely oriented. The photoelectrochemical response of the films in Na-p olysulphide solution shows distinct n-type behaviour.