Surface State Controlled Superior Photodetection Properties of Isotype n-TiO2/In2O3 Heterostructure Nanowire Array With High Specific Detectivity

An integrate approach of growing vertical axial heterostructure (AH) nanowire (NW) with TiO2 and In2O3 may provide an alternative route for efficient improvement in internal gain and photosensitivity. Here, TiO2/In2O3 AH NW is synthesized on p-Si substrate inside e-beam evaporator using glancing angle deposition technique. Field emission gun scanning electron microscopy confirms the growth of vertically aligned TiO2/In2O3 AH NW NWs. Averagely, 1.5 times absorption enhancement is observed in TiO2/In2O3 AHNWcompared to the as-deposited TiO2 NW sample. The designed TiO2/In2O3 AH NW device shows superior optoelectronic performance in terms of fast response (T-R = 52.96 ms and T-F = 89.32 ms), high photosensitivity (similar to 1000 times), and good rectification ratio (similar to 10 times). In addition, maximum responsivity (11.17 A/W), high internal gain (36.8), superior detectivity (3.14 x 10(14) Jones) and low noise equivalent power (8.92 x 10(-15) W) are obtained for TiO2/In2O3 AH NW. A large linear dynamic range value of 59.14 dB is obtained for TiO2/In2O3 AHNW due to prolonged carrier recombination lifetime, multiple light scattering within NWs and efficient charge separation along the length of heterostructure. Therefore, the outstanding optoelectronic properties obtained with TiO2/In2O3 AH NW will ensure a wider promising electronic and optoelectronic device applications.