ZnSe homoepitaxial layers grown at very low temperature by atmospheric pressure metalorganic vapor-phase epitaxy

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Abstract
ZnSe homoepitaxial layers with high crystalline quality were grown on (100) ZnSe substrates (grown by the iodine vapor transport method) between 190 and 250 °C. The surface morphologies of homoepitaxial layers (homoepilayers) grown below 250 °C were all mirrorlike. The concentration of self-activated (SA) centers is related to the growth temperature. The band-edge photoluminescence (PL) intensity increases drastically with increasing temperature from 190 up to 210 °C, decreases above 210 °C, and the SA-PL intensity increases monotonically as the growth temperature increases. The mechanism of suppressing the occurrence of SA centers below 250 °C is assumed that the concentration of Zn vacancies diffused from the highly iodine-doped ZnSe substrates into the ZnSe homoepilayers reduces at this temperature region. The SA-PL intensity of the ZnSe homoepilayer with the strongest band-edge emission (grown at 210 °C) is the same or weaker than that of the best ZnSe heteroepitaxial layer (heteroepilayer). Below 200 °C, the FWHM of the ZnSe (400) diffraction is 14 arcsec which is the best value we have ever obtained, though the growth temperature seems to be too low to maintain the crystalline quality. The comparison on the crystalline quality with the ZnSe heteroepilayers is discussed in detail from the viewpoints of the epitaxial growth mechanism.