Crystal orientation dependence of deep level spectra in proton irradiated bulk β-Ga2O3

A. Y. Polyakov, N. B. Smirnov, I. V. Shchemerov, A. A. Vasilev, A. I. Kochkova, A. V. Chernykh, P. B. Lagov, Yu S. Pavlov, V. S. Stolbunov, T. V. Kulevoy, I. V. Borzykh, In Hwan Lee, Fan Ren, S. J. Pearton

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4 Citations (Scopus)

Abstract

The effects of 20 MeV proton irradiation with fluences of 5 × 1014 and 1015 p/cm2 on electrical properties of lightly Sn doped n-type (net donor concentration 3 × 1017 cm−3) bulk β-Ga2O3 samples with (010) and (−201) orientation were studied. Proton irradiation decreases the net donor density with a removal rate close to 200 cm−1 for both orientations and similar to the electron removal rates in lightly Si doped β-Ga2O3 epilayers. The main deep electron traps introduced in the β-Ga2O3 crystals of both orientations are near Ec−0.45 eV, while in Si doped films, the dominant centers were the so-called E2* (Ec−0.75 eV) and E3 (Ec−0.1 eV) traps. Deep acceptor spectra in our bulk -Ga2O3(Sn) crystals were dominated by the well-known centers with an optical ionization energy of near 2.3 eV, often attributed to split Ga vacancies. These deep acceptors are present in a higher concentration and are introduced by protons at a higher rate for the (010) orientation. Another important difference between the two orientations is the introduction in the surface region (∼0.1 μm from the surface) of the (010) of a very high density of deep acceptors with a level near Ec−0.27 eV, not observed in high densities in the (−201) orientation or in Si doped epitaxial layers. The presence of these traps gives rise to a very pronounced hysteresis in the low temperature forward current-voltage characteristics of the (010) samples. These results are yet another indication of a significant impact of the orientation of the β-Ga2O3 crystals on their properties, in this case, after proton irradiation.

Original languageEnglish
Article number035701
JournalJournal of Applied Physics
Volume130
Issue number3
DOIs
Publication statusPublished - 2021 Jul 21

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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