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 revealed 2 types of hole trap in the GaAsSbN i layer: HT1, a shallow N-related defect state (Ea ~ 0.10 to 0.12eV) and HT2, an AsGa point defect-related mid-gap defect state with Ea ~ 0.42 to 0.43eV. Reduction in growth temperature from 480 to 420C reduced the HT2 trap concentration from 4 x 1015 to 1015/cm3, while increasing the HT1 trap concentration from 1014 to 7 x 1014/cm3. 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 mid-gap 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. A ~4dBm improvement in photoresponse under 1.3µm laser excitation and approximately 8 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 mid-gap trap concentration in the sample grown at 420C.

Effect of Growth Temperature on Defect States of GaAsSbN Intrinsic Layer in GaAs/GaAsSbN/GaAs Photodiode for 1.3µm Application. S.Wicaksono, S.F.Yoon, W.K.Loke, K.H.Tan, K.L.Lew, M.Zegaoui, J.P.Vilcot, D.Decoster, J.Chazelas: Journal of Applied Physics, 2007, 102[4], 044505