Enhanced Photoresponsivity UV-C Photodetectors Using a p-n Junction Based on Ultra-Wide-Band Gap Sn-Doped β-Ga2O3 Microflake/MnO Quantum Dots

Norah Alwadai, Zohoor Alharbi, Fatimah Alreshidi, Somak Mitra, Bin Xin, Hadeel Alamoudi, Kishor Upadhyaya, Mohamed N. Hedhili, Iman S. Roqan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


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-Ga2O3 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 Ga2O3 microflakes are prepared by exfoliation. The solution-processed QDs are uniformly dropcasted on the exfoliated Sn-doped β-Ga2O3 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-Ga2O3 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.

Original languageEnglish (US)
Pages (from-to)12127-12136
Number of pages10
JournalACS Applied Materials and Interfaces
Issue number9
StatePublished - Mar 8 2023

Bibliographical note

Funding Information:
We thank KAUST for the financial support, using the base fund number BAS/1/1319-01-01.

Publisher Copyright:
© 2023 American Chemical Society.


  • deep UV detection
  • GaO nanoflake
  • heterojunction
  • p-type wide bandgap semiconductor
  • photodiode
  • quantum dots
  • visible-blind

ASJC Scopus subject areas

  • Materials Science(all)


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