Thermally stimulated currents in semi-insulating GaAs Schottky diodes and their simulation

We report the investigation of the non-irradiated and irradiated-with-pions Schottky diodes made on semiinsulating GaAs. Thermally stimulated currents have been measured experimentally and modeled numerically. To reveal the i nfluence of the single levels, we used the thermal emptying of the traps by fractional heating. Attention is paid to the comparative analysis of the d istribution of the parameters of different samples produced and processed b y the same technique, contrary to the usual approach of the analysis of a f ew different samples. The following main conclusions are drawn. First of al l, many different levels (from 8 to 12) have been found in the temperature range from 90 K to 300 K in all samples. Their activation energies range fr om 0.07 up to 0.55 eV, their capture cross-sections are 10(-22)-10(-14) cm( 2), and initial occupation is 2 x 10(11)-5 x 10(14) cm(-3). The irradiation with pions does not influence the density of most levels significantly. On the other hand, levels with activation energies of about 0.07-0.11 eV, 0.3 3-0.36 eV, 0.4-0.42 eV, and 0.48-0.55 eV have been found only in the irradi ated samples. Irradiation also increases the inhomogeneity of the crystals, which causes the scattering of the activation energies obtained by fractio nal heating technique.