Optically Detected Magnetic Resonance and Microwave Electric Field Effects in Iii-V Semiconductors

The optically detected magnetic resonance (ODMR) technique was employed at 3 and 16 GHz to study the P _{rm In} antisite defect in zinc-doped InP. A model for the competing antisite -to-acceptor and shallow-donor-to-acceptor luminescent processes was developed based on the ODMR and time resolved photoluminescence measurements. The proposed model is in good agreement with the observed ODMR effects. The ODMR technique was also used to study defects in the ternary III-V semiconducting system GaPSb. The study revealed the presence of at least three impurity or defect-related spin dependent recombination centers. No unambiguous identification of the microscopic defects or impurities was possible based solely on the 3 GHz ODMR measurements, but the tentative assignment include a residual shallow acceptor impurity (perhaps carbon), a phosphorous antisite occupying an antimony lattice site, a phosphorous interstitial and a residual shallow donor. The effects of the microwave electric field on the photoluminescent processes, frequently observed as nonresonant background signals in ODMR measurements, were investigated in a large number of binary and ternary III -V semiconductors using the microwave modulated photoluminescence (MMPL) technique. The experimental and theoretical investigations of the MMPL in III-V semiconductors revealed that changes in the donor-to-acceptor photoluminescence (PL) intensity in the binary compounds examined was due to the impact ionization of neutral donors by photoexcited free carriers accelerated in the microwave electric field. Elastic scattering processes were shown to be important in the impact ionization process. The randomization of the free carrier velocity vector in the elastic scattering processes allows the carriers to gain energy from a time varying electric field. For a fraction of the free carriers the energy gain from even a small microwave electric field is sufficient to impact ionize neutral donors. In many ternary compounds the observed MMPL signal was attributed to a thermal modulation of the PL by the microwave electric field, i.e., microwave heating.