High figure‐of‐merit gallium oxide UV photodetector on silicon by molecular beam epitaxy: a path toward monolithic integration

Partha Mukhopadhyay, Isa Hatipoglu, Tamil Selvan Sakthivel, Daniel A. Hunter, Naresh Kumar Gunasekar, Paul R. Edwards, Robert W. Martin, Sudipta Seal, Winston Vaughan Schoenfeld

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Abstract

We demonstrate a high figure-of-merit UV–C solar-blind photodetectors fabricated from polycrystalline beta-gallium oxide (β-Ga2O3) grown on n-Si substrates by plasma assisted molecular beam epitaxy (PAMBE). We developed film growth sequences for nucleation of Ga2O3 on (100) and (111) oriented Si substrates, and systematically investigate the influence of crucial growth parameters, namely substrate temperature, oxygen flow rate and plasma power on the functional properties of the photodetectors. The photodetectors show ultra-high responsivity of 837 A/W and fast ON/OFF time below 4ms observed under 248 nm illumination at –5V. In addition, they display strong rectifying properties and sharp cut-off below 280 nm with average responsivities between 10-80 A/W, detectivity on the order of 1010 Jones, and rise/fall times between 4 to 500 ms at –5V. High photoconductive gain is shown to likely be due to the mid-bandgap donor/acceptor defect levels, including oxygen vacancies in the form of self-trapped holes. We demonstrate that these defect levels can be modified by controlling the growth conditions, thereby, allowing for tailoring of the photodetector characteristics for specific applications. Our methodology represents a cost-effective solution over homoepitaxial approaches, with characteristics that meet or exceed those reported previously, offering new possibilities for on-wafer integration with Si electronics.
Original languageEnglish
Article number2000067
Number of pages13
JournalAdvanced Photonics Research
Volume2
Issue number4
Early online date8 Dec 2020
DOIs
Publication statusPublished - 7 Apr 2021

Keywords

  • UV-C photodetector
  • gallium oxide
  • molecular beam epitaxy
  • heterostructure
  • heterointegration

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