Molecular beam epitaxial studies were made, of wide band-gap (greater than 2.9eV at room temperature) MgZnSSe on (001)-oriented GaAs, by using ZnS, Mg, Zn, and Se sources. Although growth occurred under group-II rich conditions, the concentrations of S and Mg in the MgZnSSe were linear functions of the flux ratios, ZnS/Se and Mg/ZnS, at up to 35%. It was found that mirror-like surfaces and a low defect density (5 x 104/cm2) could be obtained in MgZnSSe (with a band-gap of about 3.1eV). Composition modulation, tweed-like contrast and strain contrast were detected by means of transmission electron microscopy. A miscibility gap at high S and Mg concentrations was reported for the first time. Radicals which were N-free were used as p-type dopants. In the case of MgZnSSe with a room-temperature band-gap energy of more than 2.9eV, the net acceptor concentration decreased as the band-gap energy increased.

B.J.Wu, J.M.DePuydt, G.M.Haugen, G.E.Höfler, M.A.Haase, H.Cheng, S.Guha, J.Qiu, L.H.Kuo, L.Salamanca-Riba: Applied Physics Letters, 1995, 66[25], 3462-7