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

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 1.3 μm. 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 (E_a∼0.10–0.12 eV) and (ii) HT₂: an As_Ga point defect-related midgap defect state with E_a∼0.42–0.43 eV. Reduction in growth temperature from 480 to 420 °C reduces the HT₂ trap concentration from 4×10¹⁵ to 1×10¹⁵ cm^-3, while increases the HT₁ trap concentration from 1×10¹⁴ to 7×10¹⁴ cm^-3. Reduction in the HT₂ trap concentration following growth temperature reduction was attributed to the suppression of As_Ga point defect formation. Evidence of possible change of the As_Ga midgap state to a shallow level defect due to the formation of (As_Ga–N_As) pairs was also suggested to have increased the HT₁ trap concentration and reduced the HT₂ trap concentration. An ∼4 dBm improvement in photoresponse under 1.3 μm laser excitation and approximately eight times reduction in dark current at -8 V reverse bias were attributed to the reduction in the overall trap concentration and mainly the reduction of the As_Ga-related midgap trap concentration in the sample grown at 420 °C. [ABSTRACT FROM AUTHOR]