| Our study covers investigation of substrate materials for GaN epitaxy, III-nitride epilayers, multiple quantum wells, and device prototypes to follow the main structural features and peculiarities in dynamics of nonequilibrium carriers, which determine the performance of wide-band-gap III-nitride violet and UV emitters.; Our results indicate that the long-wavelength EL band peaked at 330 nm has a rise time of 75 ns, which is longer than that of the main narrow band peaked at 285 nm due to band-to-band recombination (less than 10 ns). The quantum efficiency of the light emitting diode (LED) emission can be increased at least by a factor of 10 by reducing the long-wavelength spectral component.; GaN layers grown on Mace bulk AlN have a higher density of localized states than the layers grown on the Al face. Different effective heights of barriers for transitions to the centers of nonradiative recombination and different slopes in dependence of the PL intensity on the excitation power density show that different kinds of nonradiative recombination centers are involved in the GaN samples grown on Al- and N-face of bulk AlN.; PL spectroscopy proves high quality of MQW structures consisting of Al 0.5Ga0.5N wells and AlN barrier layers deposited on AlN bulk single crystal substrates. Stimulated emission at 258 nm was demonstrated in these structures. The PL dynamics with increasing temperature and power density of photoexcitation indicates the presence in the quantum wells of a high density of shallow localized states with a narrow energy distribution in AlGaN MQWs grown on bulk AlN substrates. Such localization might prevent the nonequilibrium carriers from reaching centers of nonradiative recombination and, thus, is favorable for the efficient light emission. These results show that AlN is a promising substrate material for solid-state light emitters and detectors in deep UV region.; LITG technique is demonstrated to be useful for evaluation of ambipolar diffusion coefficient, carrier lifetime and mobility as well as for mapping V-doped wafers. Application of this technique demonstrated big differences of undoped and V-doped 6H-SiC wafers in view of carrier lifetimes (400 +/- 10 ps and 130 +/- 5 ps) and diffusion coefficients (2.7 +/- 0.2 cm2s-1 and 0.9 +/- 0.5 cm2s-1). |
