Abstract
Non-conventional spectroscopy techniques, in which the electron paramagnetic resonance (EPR) and optical absorption (OA) Spectra are thermally detected (TD) via a carbon thermometer at liquid-helium-4 temperatures, are used to investigate the GaP:V system in n-type samples. New TD-EPR results are described. The presence of most of the TD-EPR lines appears to correlate with that of the V2+ TD-OA signal. A comparison of the photo-induced effects on the TD-OA V3+ and V2+ spectra and on the TD-EPR lines is made in order to help in the identification of the latter. A set of resonances in TD-EPR is attributed to a V2+(II) centre, with a 4T1 ground state, similar to that seen in GaAs:V. A trigonal model where V2+(II) is part of a complex in which one of the neighbouring P ions is replaced by a defect is used to fit the experimental data. Further TD-EPR lines can be due to another V2+ ion having also a 4T1 ground state but which appears to be different from V2+(II).