PHOTOLUMINESCENCE AND EXCITATION SPECTROSCOPY OF ZNTE/GAAS EPILAYERS GROWN BY HOT-WALL EPITAXY

Using reflection, photoluminescence and excitation spectroscopy we carried out systematic studies on the optical properties in the excitonic energy region of ZnTe/GaAs epilayers grown by hot-wall epitaxy (HWE). We calculate the strain magnitude, the light-hole (Ih) and heavy-hole (hh) energy shifts, and compare the theoretical values with the experimentally observed energy positions in ZnTe films of different thicknesses. The detected energy distance between the free excitons X(Ih) and X(hh) decreases with increasing layer thickness, indicating a relaxation of the thermally induced strain in the ZnTe layer. Additionally, we investigate the incorporation of different impurities, the electronic structure of the main acceptor-exciton complexes (A0, X) and the high-photon-density spectra of the ZnTe films. For increasing densities a biexciton band appears, and we determine the biexciton binding energy to amount to about 3.3 +/- 1.0 meV.