COMPOSITION CONTROL BY PHOTOIRRADIATION IN MOVPE OF ZNCDSE AND ZNCDS ALLOY LAYERS AND MULTILAYERED STRUCTURES

In the metalorganic vapor-phase epitaxial growth of ZnxCd1-xSe and ZnxCd1-xS alloys with the source precursors of DMZn-DMCd-DESe and DMZn-DMCd-DES, respectively, the solid composition x of zinc in epitaxial layers was remarkably increased with photo-irradiation at a constant gas-phase composition. This phenomenon was interpreted from mass analysis as indication that photo-irradiation enhances the decomposition of DMZn while hardly influencing the decomposition of DMCd, because DMCd is thermally decomposed at low temperature and there remains almost no opportunity for further decomposition by photo-irradiation. By keeping the gas-phase composition constant, the control of irradiation/non-irradiation sequences successfully resulted in fabrication of ZnCdSe or ZnCdS multi-layered structures, where the solid composition of zinc in a constituent layer grown with irradiation was larger than that in a layer grown without irradiation.