High-detectivity solar-blind deep UV photodetectors based on cubic/monoclinic mixed-phase (InxGa1−x)2O3 thin films

• Published in: Journal of alloys and compounds Vol. 965; p. 171473
• Main Authors: Qi, Kai, Fu, Shihao, Wang, Yuefei, Han, Yurui, Fu, Rongpeng, Gao, Chong, Ma, Jiangang, Xu, Haiyang, Li, Bingsheng, Shen, Aidong, Liu, Yichun
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 25-11-2023
• Subjects: Chemical vapor deposition; Mixed-phase (InxGa1−x)2O3; Solar-blind photodetector; Ultralow dark current; Solar-blind photodetector; Mixed-phase (InxGa1−x)2O3; Chemical vapor deposition; Ultralow dark current
• ISSN: 0925-8388
• DOI: 10.1016/j.jallcom.2023.171473

Mixed-phase (InxGa1−x)2O3 films were fabricated by excessive doping of In in Ga2O3 and by controlling different precursor weight ratios of monoclinic Ga2O3 and cubic In2O3. X-ray diffraction and transmission spectra showed that excessive indium doping over the solubility of In in Ga2O3 causes phase separation and the formation of films in which monoclinic (InxGa1−x)2O3 (β-IGO) and cubic (InxGa1−x)2O3 (c-IGO) coexist. The (InxGa1−x)2O3 photodetector with a ratio of Ga2O3: In2O3 = 10: 1 is highly sensitive to solar-blind radiation with an ultralow dark current of 0.03 pA and a large I254 nm/Idark up to 2.53 × 107 under − 7 V bias. Under a bias of 10 V, the device has a high responsivity and detectivity of 0.97 A/W and 4.62 × 1014 Jones, respectively. The ultralow dark current is attributed to the interface states at the grain boundaries between β-IGO and c-IGO in the mixed-phase films, which can trap electrons and form potential barriers that inhibit carrier transport. Irradiation under 254 nm light generates electron-hole pairs in β-IGO and c-IGO, which are separated by internal electric fields. The holes are captured during migration by potential traps, causing continuous electron injection and sweep-out until the holes escape from the traps, resulting in a device with good performance. The proposed alloying method could be used to fabricate future photoelectric devices.
•Intentionally excessive doping of In2O3 in Ga2O3 to synthesize (InxGa1−x)2O3 thin films.•The (InxGa1−x)2O3 thin films-based photodetector has an ultralow dark current and a large light-to-dark current ratio.•Under illumination, the photogenerated holes will be captured by the potential trap, resulting in a high gain.•The (InxGa1−x)2O3 thin films-based photodetector avoids shoulder peak detection issues.