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.

Systematic investigations are performed on the surface morphology, structural properties, and p-type dopability of BeTe epilayers grown on GaAs (001) by molecular beam epitaxy under various growth temperatures and p(Te)/p(Be) flux ratios. A phase diagram for surface reconstruction is obtained with regard to the BEP (beam equilibrium pressure) ratio of p(Te)/p(Be) and growth temperature. Irrespective of growth temperature (300–500 °C), a surface phase transition from weak (4×1) to (2×1) reconstruction occurs near p(Te)/p(Be)∼10 as the p(Te)/p(Be) value increases. Epilayers grown at a low Te pressure of p(Te)/p(Be)⩽10 show Be droplets on the surface as observed by atomic force microscopy, which eventually leads to degraded crystallinity. It is noted that such growth features are different from conventional II–VI compounds. The differences in growth features are discussed in terms of the relationships between the equilibrium vapor pressures of the compound and constituent elements. By optimizing growth conditions, i.e., flux ratio of 15<p(Te)/p(Be)<20, epilayers with high structural quality and smooth surface are obtained. Good correlation between the surface morphology and crystallinity is found. p-type BeTe layers doped with N are grown using a radio-frequency nitrogen plasma source. The net acceptor concentration increases as the p(Te)/p(Be) flux ratio is decreased. It is shown that p-BeTe with high hole concentrations above 6×1018 cm−3 can be readily grown.