ELECTRONIC-PROPERTIES OF IRON IN LIQUID-PHASE-EPITAXY-GROWN IN0.49GA0.51P

The optical and thermal characteristics of deep iron acceptors doped into liquid-phase-epitaxy-grown In0.49Ga0.51P were studied using photocapacitance and deep-level transient spectroscopy. The spectral dependence of the Fe-acceptor photoionization cross section was determined. Optical thresholds for 5E and 5T2 of the crystal-field-split Fe2+ level were 0.78 and 1.15 eV, leading to a crystal-field-split energy of 0.37 eV. The difference between optical and thermal thresholds for 5E was 40 meV. From this we concluded that the coupling between the Fe level and lattice vibration of In0.49Ga0.51P was weak. The photoionization spectrum fit well with the Lucovsky model calculation. Nonexponential capacitance transients were observed for both the optical and thermal excitation of holes, which were caused by alloy broadening of the Fe level. We used a stochastic model of disordered atomic arrangement to analyze the alloying effects, and obtained an effective level width of 90 meV. We also discuss carrier emission from the energetically broadened level.