Growth and characterization of beryllium-based II–VI compounds

Abstract

We report on the growth and characterization of beryllium–chalcogenide layers prepared on GaAs (100) by molecular beam epitaxy. Be- and Te-terminated BeTe surfaces show (4×1) and (2×1) reconstructions, respectively. The stability of each surface is investigated by reflection high energy electron diffraction as a function of substrate temperature. The dependence of growth rate of BeTe on growth temperature and Be cell temperature is investigated. The best full width at half maximum (FWHM) of a (400) x-ray rocking curve of BeTe is 78 arcsec. The dependence of the ZnBeSe energy gap on Be composition is obtained by four-crystal x-ray diffraction (XRD) and low temperature photoluminescence measurements. The energy gap of Zn1−xBexSe varies as Eg=0.0107x+2.790 (eV) for small Be composition (x<0.25) at 77 K. Lattice-matched ZnBeSe (Eg=2.82 eV) and ZnMgBeSe (Eg=2.975 eV) layers show narrower XRD peaks, the FWHM values of which are 64 and 21 arcsec, respectively. The variation of FWHM of x-ray rocking curve due to lattice misfit is investigated for ZnMgBeSe quaternaries with various lattice misfits extending from compressive to tensile strain. The FWHM value under compressive strain increases more steeply with lattice misfit than that under tensile strain.