Bulk and interface deep levels in InGaP/GaAs heterostructures grown by tertiarybutylphosphine-based gas source molecular beam epitaxy

InGaP/GaAs heterostructures were grown by gas source molecular beam epitaxy (GSMBE) using tertiarybutylphosphine (TBP), and their bulk and interface deep levels were studied by deep level transient spectroscopy (DLTS), photoluminescence (PL), and cathodoluminescence (CL) techniques. Five bulk deep levels related to phosphorus vacancies and their complexes were detected by DLTS. They could be almost completely removed under a TBP flow rate higher than 4-5 seem, accompanied by a marked increase of the bulk band edge PL intensity. On the other hand, InGaP/GaAs heterostructures grown under high TBP flow rates showed anomalous PL and CL peaks near 1.7 eV. CL study performed by changing the acceleration voltage showed that these peaks were heterointerface related, most likely due to phosphorus vacancies near interfaces. InGaP/GaAs quantum wells (QW) without such peaks and with intense QW emission were successfully formed by avoiding phosphorous vacancy formation through elimination of growth interruption.