DLTS study of heat treatments on n-CdTe crystals

DLTS measurements were carried out on Schottky barriers formed on the surfaces of n -CdTe:In crystals heated in argon gas. Four electron trap levels were detected. The carrier concentration near the surface decreased to less than a tenth as a result of heat treatments at 350 or 400°C for 1 hour. A sample heated at 400°C showed a steep decrease in the carrier concentration near the surface. The concentration of an electron trap level ( E C - E T =0.34 eV) was reduced by heat treatments. Heat treatments at temperatures higher than 350°C for 1 hour seemed to induce some defects related to cadmium vacancies or tellurium interstitials, which compensate donors and reduce the concentration of the trap level near the surfaces of CdTe.