Investigation of deep electronic centers in low-temperature grown GaAs using extremely thin layers

We report on an approach to investigate the deep electronic defect centers in low-temperature grown GaAs (LT-GaAs). Using an extremely thin LT-GaAs la yer (comparable with the penetration depth of an electric field in bulk mat erial) incorporated in the i layer of a p-i-n diode, we are able to charge or to deplete the deep centers in the energy gap by applying a reverse bias . The corresponding space charge is monitored by the field changes across t he LT-GaAs layer, both optically by Franz-Keldysh experiments and electrica lly by n-channel conductance changes. From our results, we derive a deep tr ap density of 10(18) cm(-3) centered at around 500-700 meV below the conduc tion band. (C) 2000 American Institute of Physics. [S0003-6951(00)02241-5].