Deep levels in GaN studied by deep level transient spectroscopy and Laplace transform deep-level spectroscopy

In this study we present the results of investigations on Schottky Au-GaN diodes by means of conventional DLTS and Laplace DLTS methods within the temperature range of 77-350 K. Si-doped GaN layers were grown by Molecular Beam Epitaxy technique (MBE) on sapphire substrates. DLTS signal spectra revealed the presence of four majority traps: two hightemperature and two low-temperature peaks. Using LDLTS method and Arrhenius plots the activation energy and capture cross sections were obtained. For two high-temperature majority traps they are equal to E1 = 0.65 eV, sigma(1) = 8.2 x 10(-16)cm(2) and E2 = 0.58 eV, sigma(2) = 2.6 x 10(-15) cm(2) whereas for the two low-temperature majority traps E3 = 0.18 eV, sigma(3) = 9.72 x 10(-18) cm(2) and E4 = 0.13 eV, sigma(4) = 9.17 x 10(-18) cm(2). It was also found that the traps are related to point defects. Possible origin of the traps was discussed and the results were compared with the data found elsewhere [1-5].