Enhanced Photoresponsivity UV-C Photodetectors Using a p-n Junction Based on Ultra-Wide-Band Gap Sn-Doped β-Ga 2 O 3 Microflake/MnO Quantum Dots

• Published in: ACS applied materials & interfaces Vol. 15; no. 9; pp. 12127 - 12136
• Main Authors: Alwadai, Norah, Alharbi, Zohoor, Alreshidi, Fatimah, Mitra, Somak, Xin, Bin, Alamoudi, Hadeel, Upadhyaya, Kishor, Hedhili, Mohamed N, Roqan, Iman S
• Format: Journal Article
• Language: English
• Published: United States 08-03-2023
• Subjects: quantum dots; Ga2O3 nanoflake; heterojunction; p-type wide bandgap semiconductor; photodiode; visible-blind; deep UV detection
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.2c18900

Solar-blind self-powered UV-C photodetectors suffer from low performance, while heterostructure-based devices require complex fabrication and lack p-type wide band gap semiconductors (WBGSs) operating in the UV-C region (<290 nm). In this work, we mitigate the aforementioned issues by demonstrating a facile fabrication process for a high-responsivity solar-blind self-powered UV-C photodetector based on a p-n WBGS heterojunction structure, operating under ambient conditions. Here, heterojunction structures based on p-type and n-type ultra-wide band gap WBGSs (i.e. both are characterized by energy gap ≥4.5 eV) are demonstrated for the first time; mainly p-type solution-processed manganese oxide quantum dots (MnO QDs) and n-type Sn-doped β-Ga
O
microflakes. Highly crystalline p-type MnO QDs are synthesized using cost-effective and facile pulsed femtosecond laser ablation in ethanol (FLAL), while the n-type Ga
O
microflakes are prepared by exfoliation. The solution-processed QDs are uniformly dropcasted on the exfoliated Sn-doped β-Ga
O
microflakes to fabricate a p-n heterojunction photodetector, resulting in excellent solar-blind UV-C photoresponse characteristics (with a cutoff at ∼265 nm) being demonstrated. Further analyses using XPS demonstrate the good band alignment between p-type MnO QDs and n-type β-Ga
O
microflakes with a type-II heterojunction. Superior photoresponsivity (922 A/W) is obtained under bias, while the self-powered responsivity is ∼86.9 mA/W. The fabrication strategy adopted in this study will provide a cost-effective means for the development of flexible and highly efficient UV-C devices suitable for energy-saving large-scale fixable applications.