Current–voltage characteristics and deep-level study of GaN nanorod Schottky-diode-based photodetector

Understanding the metal/semiconductor interface is very significant for real-time optoelectronic device applications. In particular, the presence of interface states and other defects is detrimental to photodetector applications. In this study, the electrical transport properties of a pristine gallium nitride (GaN) nanorod (NR)-based Schottky diode are demonstrated at different temperatures by current–voltage characteristics in the range of 200–360 K. An enhancement in the Schottky barrier height (0.65 eV for hydrogen-passivated GaN NRs compared to 0.56 eV for pristine ones) is noticed. The effect of deep traps residing within the forbidden gap of GaN NRs is investigated using deep-level transient spectroscopy. Two deep defects are found at E _C − 0.19 eV and E _C − 0.31 eV in pristine GaN NRs; the E _C − 0.31 eV defect peak is attributed to V _Ga or nitrogen interstitials. After hydrogenation the peak at E _C − 0.31 eV is suppressed and that at E _C − 0.19 eV remains unchanged. The hydrogenated GaN NRs show a high photoresponse, which is nearly 2.83 times higher than that of pristine GaN NRs. The hydrogenated GaN NRs exhibit a photoresponsivity of 4.7 $\times$ 10⁻³ A W⁻¹ and detectivity of 1.24 $\times$ 10¹⁰ Jones under UV illumination of λ = 382 nm. The enhanced performance is attributed to the deep defect passivation by hydrogenation along with the surface-state-free interface between the GaN NRs and metal contacts. The experimental results demonstrate the significance of hydrogen treatment use in the fabrication of GaN-based optoelectronic devices. (paper)