High-quality epitaxial growth of ZnSe on (100) ZnSe by atmospheric pressure metalorganic vapor phase epitaxy

Single crystalline layers of undoped ZnSe have been grown on ZnSe substrates at 250 °C by atmospheric pressure metal organic vapor-phase epitaxy using dimethylzinc and hydrogen selenide (H2 Se). The substrates are ZnSe wafers with (100) orientation cut from bulk crystals grown by iodine vapor transport. A homoepitaxial layer (homoepilayer) of ZnSe with excellent crystallographic properties, as revealed by double crystal x-ray diffraction, was obtained. The full width at half maximum (FWHM) of the (400) diffraction pattern was 38 arcsec, which was superior to the crystallographic property (the FWHM was 250 arcsec) of the heteroepitaxial layer (heteroepilayer; a GaAs substrate was used). However, the intensity of deep emissions near 560 nm (PL at 77 K) is several times stronger than that of the heteroepilayer. The origin of deep emissions is not supposed to be due to iodine or copper diffused from the ZnSe substrate but to complexes between Zn vacancies and impurities in the layer.