Excess Of Gallium Research Articles

Stoichiometry of the ternary semiconductor CuGaS2 : 57Fe as determined by Mössbauer spectroscopy

Mössbauer experiments performed on iron−doped CuGaS2 showed the iron to be present in two valence states, Fe2+ and Fe3+. The ratio R of the Fe2+ to Fe3+ concentrations is stoichiometry dependent and could be controlled by adjusting the stoichiometry of the starting elements. Incorporation of iron during synthesis and growth from a stoichiometric mixture of the elements leads to R smaller than 0.01, i.e., almost only to Fe3+. With a gallium excess of 5%, R becomes as high as 1.2. Subsequent annealing of the latter samples in a sulphur atmosphere, oxidizes part of the divalent iron into Fe3+, resulting in R=0.3. Finally, the consequences of a transition−metal contamination upon the electrical properties of this semiconductor are pointed out.

Growth conditions and morphological pecularities of gallium phosphide whiskers obtained by thermal evaporation in vacuum

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