Compensating defects and electrical activation of donors in CdS

Electrical deactivation of donors in CdS was studied by using Perturbed gam ma gamma Angular correlation (PAC) spectroscopy and temperature dependence of Hall mobility, resistivity, and free-carrier concentration. PAC spectra and electrical properties were monitored as a function of thermal treatment either under S or Cd pressure in a temperature range from RT to 1073 K. Fo r samples annealed above 800 K under S pressure, Hall effect showed increas ed electrical compensation whereas PAC detected spontaneous creation of cad mium vacancies, V-Cd, via the formation of (I-Cd-V-Cd) pairs. The increase of the concentration of compensating accepters, determined from electrical measurements, precisely correlates with the increase of the concentration o f(In-Cd-V-Cd) pairs found by means of PAC. In contrast to that, thermal tre atment under Cd pressure up to 1073 K does not provoke the formation of com pensating native defects up to [In] > 10(19)/cm(3). (C) 1999 Elsevier Scien ce B.V. All rights reserved.