LOW-TEMPERATURE GROWTH AND PLASMA-ENHANCED NITROGEN DOPING OF ZNSE BYMETALORGANIC VAPOR-PHASE EPITAXY

The combination of diisopropylselenide (DIPSe) and diethylzinc (DEZn) was used to grow ZnSe by metalorganic vapour phase epitaxy (MOVPE). Th e results are compared with those obtained from samples grown with die thylselenide (DESe) and DEZn. Furthermore, we analysed the influence o f plasma stimulation of DIPSe and DESe, as well as plasma enhanced nit rogen doping. Plasma stimulated growth with DESe at 480-degrees-C resu lts in ZnSe which shows resolved free and bound excitons and negligibl e deep centre emissions in 11 K PL spectra. By using DIPSe without pla sma stimulation, the kinetically controlled growth regime was found in the temperature range from 380 to 480-degrees-C. In PL only broad dis tributed emissions from 2.4 to 2.78 eV were observed, arising from imp urities in the Se precursor. With plasma enhancement the diffusion con trolled growth regime was extended down to 330-degrees-C. In the PL sp ectra, excitonic emissions were found beside the emission band (2.4-2. 78 eV). Deep centre emission (2.0 eV) appeared only for T(D) < 360-deg rees-C. Doping experiments were carried out by using plasma precrackin g of the Se precursor and simultaneously stimulating nitrogen dopant g as in a plasma. The donor-acceptor pair (DAP) emission of the doped la yers increases for decreasing growth temperatures (440 to 360-degrees- C), if DIPSe and DEZn are used as precursors. Increasing the N2 flux c auses an increasing nitrogen concentration. Samples grown in N2 carrie r gas at 380-degrees-C show a maximum measured nitrogen concentration of 1.7 X 10(18) cm-3 . The layers were highly compensated, due to the impurities in the Se precursor and to additional hydrogen and carbon i ncorporation.