ELECTRON-PARAMAGNETIC-RESONANCE STUDY OF A NATIVE ACCEPTOR IN AS-GROWN ZNGEP2

Electron paramagnetic resonance (EPR) has been used to investigate an acceptor in as-grown single crystals of ZnGeP2. The spectra are characterized by equally spaced triplets with 1:2:1 intensity ratios representing hyperfine interactions (varying from 35 to 55 G in magnitude) with two equivalent phosphorous nuclei. Their angular dependence shows that there are four crystallographically equivalent orientations of the defect. The principal values of the g matrix are 2.002, 2.021, and 2.074 and the corresponding principal axes, at one of the four sites, are the [011], [100], and [01 1] directions, respectively. Two possible models are suggested for this acceptor: Either a zinc vacancy (V(Zn)) or a zinc ion on a germanium site (Zn(Ge)). It also is suggested that the acceptor responsible for the EPR signal is the same acceptor, namely AL1, that gives rise to a dominant near-infrared absorption band.