Effect of growth temperature on defect states of GaAsSbN intrinsic layer in GaAs∕GaAsSbN∕GaAs photodiode for 1.3μm application

Abstract

A GaAsSbN layer closely lattice matched to GaAs was used as an intrinsic layer (i layer) in a GaAs∕GaAsSbN∕GaAs p-i-n photodiode with response up to 1.3μm. Deep level transient spectroscopy measurement on the GaAs∕GaAsSbN∕GaAs reveals two types of hole traps (HTs) in the GaAsSbN i layer; (i) HT1: a shallow N-related defect state (Ea∼0.10–0.12eV) and (ii) HT2: an AsGa point defect-related midgap defect state with Ea∼0.42–0.43eV. Reduction in growth temperature from 480to420°C reduces the HT2 trap concentration from 4×1015to1×1015cm−3, while increases the HT1 trap concentration from 1×1014to7×1014cm−3. Reduction in the HT2 trap concentration following growth temperature reduction was attributed to the suppression of AsGa point defect formation. Evidence of possible change of the AsGa midgap state to a shallow level defect due to the formation of (AsGa–NAs) pairs was also suggested to have increased the HT1 trap concentration and reduced the HT2 trap concentration. An ∼4dBm improvement in photoresponse under 1.3μm laser excitation and approximately eight times reduction in dark current at −8V reverse bias were attributed to the reduction in the overall trap concentration and mainly the reduction of the AsGa-related midgap trap concentration in the sample grown at 420°C.