HYPERFINE INTERACTIONS IN THE CUBIC SEMICONDUCTOR CDO

The time-differential perturbed angular correlation technique has been applied using In111 probes, which decay through electron capture to Cd111, to study the hyperfine interaction in cubic cadmium oxide, in the temperature range RT740°C (RT denotes room temperature). The main fraction of probes are located in perfect-lattice sites, with null electric field gradient in agreement with crystalline-structure considerations. Around 25% of the total intensity shows an electric-field-gradient distribution around Vzz=0. This corresponds to probes located in sites perturbed by the vicinity of oxygen vacancies in the lattice. The temperature-independent behavior of the measured hyperfine parameters is discussed in terms of conductivity and band-structure properties of the semiconductor. No time-dependent interaction arising from nuclear electron-capture aftereffects are seen in this experiment. This is in agreement with a previously reported model of aftereffect processes which states that only holes trapped in impurity levels inside the band gap of the semiconductor can give rise to detectable fluctuating interactions. © 1990 The American Physical Society.