Comprehensively Enhanced Performance of MISIM β-Ga₂O₃ Solar-Blind Photodetector Inserted With an Ultrathin Al₂O₃ Passivation Layer

Recently,
$\beta $
-Ga2O3 solar-blind photodetectors (PDs) have been of great interest, and the attempts to improve their device performance have been extensively explored. However, surface passivation, a critical technique that has been widely explored in other electronic and optoelectronic devices for the enhancement of performance and ambient stability, has been rarely reported in the field of
$\beta $
-Ga2O3 solar-blind PDs. Herein, the
$\beta $
-Ga2O3 metal-insulator–semiconductor-insulator–metal (MISIM) solar-blind PDs passivated with ultrathin Al2O3 layers were fabricated and comparatively investigated. The physical mechanisms behind the passivation technique are in-depth discussed as well. It was found that the device passivated with a 3-nm Al2O3 layer not only has lower dark current but also exhibits improved photocurrent as well as responsivity due to the change of dominant carrier-transport mechanism at metal/semiconductor (M/S) interface and the effective physical isolation that eliminates the oxygen chemisorption/desorption process at the active area, resulting in the highest competitive responsivity and specific detectivity of 83.3 A/W and
$1.35\times 10^{{15}}$
Jones, respectively, among the fabricated devices. This reveals that the key factor for the comprehensive improvement of
$\beta $
-Ga2O3 solar-blind PDs lies in precisely controlling the deposition thickness of Al2O3 passivation layer. This work not only provides an alternative pathway for comprehensively enhancing the performance of
$\beta $
-Ga2O3 solar-blind PD, but also suggests an effective technique for reducing its energy consumption and noise level without degrading the other performance such as sensitivity and response speed.