(InxGa1−x)2O3 Thin Film Based Solar‐Blind Deep UV Photodetectors with Ultra‐High Detectivity and On/Off Current Ratio. Issue 7 (30th January 2022) - Chen, Wenshan
Abstract: This work reports the fabrication of high performance solar‐blind deep‐UV photodetectors using (In x Ga1 − x )2 O3 thin films grown on Al2 O3 (0001) substrates. The In contents in (In x Ga1 − x )2 O3 are controlled at x = 0, 0.1 and 0.2, whereas a higher In content leads to phase segregation of Ga2 O3 and In2 O3 . The bandgaps of (In x Ga1 − x )2 O3 films are tuned from 4.93 eV for Ga2 O3 to 4.67 eV for (In0.2 Ga0.8 )2 O3 . Schottky‐type photodetectors based on metal−semiconductor−metal structure were fabricated. The (In0.1 Ga0.9 )2 O3 photodetector is highly sensitive to solar‐blind UV spectrum and achieves a large on/off current ratio of over 10 8, a remarkable specific detectivity of 4.5 × 10 16 Jones with a prominent responsivity of 23.3 A W − 1 . Such enhanced performance compared to Ga2 O3 is associated with In modulated optical and electronic properties. High‐resolution X‐ray photoemission spectroscopy was used to study the interfacial electronic structure at the semiconductor−metal interface. A large Schottky barrier height of 1.31 eV was found for (In0.1 Ga0.9 )2 O3 devices, accounting for the low dark current. More importantly, the incorporation of In introduces In 4 d states hybridizing with O 2 p at top of the valence band of (In0.1 Ga0.9 )2 O3, which increases the optical absorption to generate a higher density of photocarriers, and therefore results in greater photocurrents. Abstract : (In x Ga1− x )2 O3 thin film based solar‐blind deep‐UV photodetectors achieve ultra‐high on/off current ratio of over 10 8 . A large Schottky barrier height in (In x Ga1− x )2 O3 devices accounts for the low dark current. And the incorporation of In introduces In 4 d states hybridizing with O 2 p at top of the valence band of (In x Ga1− x )2 O3 resulting in high photocurrent.