Refractive index measurements of ZnSe-based ternary epitaxial layers grownby molecular-beam epitaxy on GaAs (100)

ZnSe-based II-VI ternary alloys, such as ZnBeSe, ZnMgSe, and ZnCdSe, have b een shown to be excellent candidates for light-emitting device applications in the short-wavelength visible range. Since design of optical semiconduct or devices requires knowledge of refractive indices of all materials involv ed, we studied refractive indices of Zn1-xBexSe, Zn1-xMgxSe, and Zn1-xCdxSe epitaxial layers. The samples were grown by molecular-beam epitaxy in mole fractions ranges between 0 less than or equal to x less than or equal to 0 .81, 0 less than or equal to x less than or equal to 0.59, and 0 less than or equal to x less than or equal to 0.57 for Zn1-xBexSe, Zn1-xMgxSe, and Zn 1-xCdxSe, respectively. The alloy concentration x was determined by x-ray d iffraction. All samples exhibited very high crystalline quality, even at re latively high values of x. A prism-to-film. coupler technique, which involv es optical tunneling via evanescent fields, was employed to accurately dete rmine the indices of refraction. The variation of the refractive index with alloy composition at room temperature was determined at the wavelength of 632.8 nm. (C) 1999 American Vacuum Society. [S0734-211X(99)03503-9].