Photo-assisted growth and characterization of ZnxCd1−xS by MOVPE

We will describe the heteroepitaxial growth of the ternary alloy ZnxCd1−xS using photo-assistance. We illuminated the layers during the growth with a xenon lamp with visible photons having an energy higher than the band-gap of the material. The light intensity of the beam was limited to be less than 100 mW/cm2. By using such a process we could increase the Zn content of the illuminated epilayers by Δx/x30% when grown at 400°C onto (001) GaAs substrates relatively to unilluminated epilayers. Epilayers were characterized by double-crystal X-ray diffraction and photoluminescence spectroscopy. Nearly lattice-matched epilayers exhibited a full-width at half-maximum of100 arcsec by X-ray diffraction. Concerning optical properties, low-temperature photoluminescence spectra have shown, for illuminated and unilluminated epilayers, a strong near-band-edge emission peaking at 2.80 eV for x = 0.4. The effect of light on the change of the Zn content will be investigated from a fundamental point of view and for the prospect of growing quantum wells or superlattices by alternating the illumination/unillumination growth sequences.