The photoluminescence of the thermo-treated silicon

At the present work the influence of the thermal defects and thermal treatments on the near-edge photoluminescence (PL) is investigated. Starting from the assumption about the bulk defect influence on the PL intensity, the thermal treatments in the dry nitrogen ambient at the temperatures T=300-1050 degrees C were carried out. The PL intensity growths in the T = 400-500 degrees C region. As the temperature increases, the PL decreases in the region T = 600-650 degrees C and has a rather growth at the T = 700 degrees C. The PL vanishes at T = 900 C and higher. In order to control the PL behavior after the T = 1050 degrees C treatment the thermal-treated sample was repeatedly annealed at the same temperature region 300-1050 degrees C. The sample shows the same regions of PL intensity growth and decreasing but at the greatly less level. On the basis of our experimental data one can assume generation of the thermal defects during the crystal growth and treatments which leads to generation of the traps for nonequilibrium carriers. Devastation of traps leads to radiating recombination giving contribution to the near-edge PL at 1.084 eV. The coincidence of the thermal intervals for the defects annealing and reconstruction with thermal intervals for oxygen thermodonors (I and II types) generation and annealing permit us to suggest the traps formation by oxygen thermodonors with Ec-(0.09-0.15 eV) level. Within the framework of our interpretation the observed PL acts as the check method for Si crystal characterization on the presence of the oxygen thermodefects. (C) 2009 Elsevier B.V. All rights reserved.