Role of defects in ultra-high gain in fast planar tin gallium oxide UV-C photodetector by MBE

Partha Mukhopadhyay; Isa Hatipoglu; Ymir K. Frodason; Joel B. Varley; Martin S. Williams; Daniel A. Hunter; Naresh K. Gunasekar; Paul R. Edwards; Robert W. Martin; Feng Wu; Akhil Mauze; James S. Speck; Winston V. Schoenfeld

doi:10.1063/5.0107557

Role of defects in ultra-high gain in fast planar tin gallium oxide UV-C photodetector by MBE

Partha Mukhopadhyay, Isa Hatipoglu, Ymir K. Frodason, Joel B. Varley, Martin S. Williams, Daniel A. Hunter, Naresh K. Gunasekar, Paul R. Edwards, Robert W. Martin, Feng Wu, Akhil Mauze, James S. Speck, Winston V. Schoenfeld

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Abstract

We report ultra-high responsivity of epitaxial (Sn_xGa_1-x)₂O₃ (TGO) Schottky UV-C photodetectors and experimentally identified the source of gain as deep-level defects, supported by first principles calculations. Epitaxial TGO films were grown by plasma-assisted molecular beam epitaxy on (-201) oriented n-type β-Ga₂O₃ substrates. Fabricated vertical Schottky devices exhibited peak responsivities as high as 3.5×10⁴ A/W at -5V applied bias under 250nm illumination with sharp cutoff shorter than 280nm and fast rise/fall time in milliseconds order. Hyperspectral imaging cathodoluminescence (CL) spectra were examined to find the mid-bandgap defects, the source of this high gain. Irrespective of different tin mole fractions, the TGO epilayer exhibited extra CL peaks at the green band (2.20 eV) not seen in β-Ga₂O₃ along with enhancement of the blue emission-band (2.64 eV) and suppression of the UV emission-band. Based on hybrid functional calculations of the optical emission expected for defects involving Sn in β-Ga₂O₃, V_Ga–Sn complexes are proposed as potential defect origins of the observed green and blue emission-bands. Such complexes behave as acceptors that can efficiently trap photogenerated holes and are predicted to be predominantly responsible for the ultra-high photoconductive gain in the Sn-alloyed Ga₂O₃ devices by means of thermionic emission and electron tunneling. Regenerating the V_Ga–Sn defect complexes by optimizing the growth techniques, we have demonstrated a planar Schottky UV-C photodetector of the highest peak responsivity.

Original language	English
Article number	111105
Number of pages	1
Journal	Applied Physics Letters
Volume	121
Issue number	11
DOIs	https://doi.org/10.1063/5.0107557
Publication status	Published - 16 Sept 2022

Keywords

defects
ultra-high gain
fast planar tin gallium oxide
UV-C photodetector
responsivity
MBE

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10.1063/5.0107557

Mukhopadhyay-etal-APL-2022-Role-of-defects-in-ultra-high-gain-in-fast-planar-tin-gallium-oxide-UV-C-photodetectorAccepted author manuscript, 2 MBLicence: Strath_1

Doctoral Training Partnership 2018-19 University of Strathclyde | Hunter, Daniel
Martin, R. (Principal Investigator), Edwards, P. (Co-investigator) & Hunter, D. (Research Co-investigator)
EPSRC (Engineering and Physical Sciences Research Council)
1/10/19 → 29/09/23
Project: Research Studentship - Internally Allocated
Nanoanalysis for Advanced Materials and Healthcare - EPSRC strategic equipment
Martin, R. (Principal Investigator), Edwards, P. (Co-investigator), Faulds, K. (Co-investigator), Florence, A. (Co-investigator), Graham, D. (Co-investigator), Sefcik, J. (Co-investigator), Ter Horst, J. (Co-investigator), Trager-Cowan, C. (Co-investigator), Uttamchandani, D. (Co-investigator) & Wark, A. (Co-investigator)
EPSRC (Engineering and Physical Sciences Research Council)
8/11/15 → 7/11/19
Project: Research
University Of Strathclyde - Equipment Account
Gachagan, A. (Principal Investigator), He, W. (Principal Investigator), Jaroszynski, D. (Principal Investigator), Martin, R. (Principal Investigator), McArthur, S. (Principal Investigator), McArthur, S. (Principal Investigator), Connolly, P. (Co-investigator), Edwards, P. (Co-investigator), Faulds, K. (Co-investigator), Florence, A. (Co-investigator), Graham, D. (Co-investigator), Leithead, B. (Co-investigator), Sefcik, J. (Co-investigator), Ter Horst, J. (Co-investigator), Trager-Cowan, C. (Co-investigator), Uttamchandani, D. (Co-investigator) & Wark, A. (Co-investigator)
EPSRC (Engineering and Physical Sciences Research Council)
1/08/13 → 28/02/23
Project: Research

Cite this

Mukhopadhyay, P., Hatipoglu, I., Frodason, Y. K., Varley, J. B., Williams, M. S., Hunter, D. A., Gunasekar, N. K., Edwards, P. R., Martin, R. W., Wu, F., Mauze, A., Speck, J. S., & Schoenfeld, W. V. (2022). Role of defects in ultra-high gain in fast planar tin gallium oxide UV-C photodetector by MBE. Applied Physics Letters, 121(11), Article 111105. https://doi.org/10.1063/5.0107557

@article{a963215672fb4828be56232a7abb05aa,

title = "Role of defects in ultra-high gain in fast planar tin gallium oxide UV-C photodetector by MBE",

abstract = "We report ultra-high responsivity of epitaxial (SnxGa1-x)2O3 (TGO) Schottky UV-C photodetectors and experimentally identified the source of gain as deep-level defects, supported by first principles calculations. Epitaxial TGO films were grown by plasma-assisted molecular beam epitaxy on (-201) oriented n-type β-Ga2O3 substrates. Fabricated vertical Schottky devices exhibited peak responsivities as high as 3.5×104 A/W at -5V applied bias under 250nm illumination with sharp cutoff shorter than 280nm and fast rise/fall time in milliseconds order. Hyperspectral imaging cathodoluminescence (CL) spectra were examined to find the mid-bandgap defects, the source of this high gain. Irrespective of different tin mole fractions, the TGO epilayer exhibited extra CL peaks at the green band (2.20 eV) not seen in β-Ga2O3 along with enhancement of the blue emission-band (2.64 eV) and suppression of the UV emission-band. Based on hybrid functional calculations of the optical emission expected for defects involving Sn in β-Ga2O3, VGa–Sn complexes are proposed as potential defect origins of the observed green and blue emission-bands. Such complexes behave as acceptors that can efficiently trap photogenerated holes and are predicted to be predominantly responsible for the ultra-high photoconductive gain in the Sn-alloyed Ga2O3 devices by means of thermionic emission and electron tunneling. Regenerating the VGa–Sn defect complexes by optimizing the growth techniques, we have demonstrated a planar Schottky UV-C photodetector of the highest peak responsivity.",

keywords = "defects, ultra-high gain, fast planar tin gallium oxide, UV-C photodetector, responsivity, MBE",

author = "Partha Mukhopadhyay and Isa Hatipoglu and Frodason, {Ymir K.} and Varley, {Joel B.} and Williams, {Martin S.} and Hunter, {Daniel A.} and Gunasekar, {Naresh K.} and Edwards, {Paul R.} and Martin, {Robert W.} and Feng Wu and Akhil Mauze and Speck, {James S.} and Schoenfeld, {Winston V.}",

year = "2022",

month = sep,

day = "16",

doi = "10.1063/5.0107557",

language = "English",

volume = "121",

journal = "Applied Physics Letters",

issn = "0003-6951",

publisher = "American Institute of Physics Publising LLC",

number = "11",

}

TY - JOUR

T1 - Role of defects in ultra-high gain in fast planar tin gallium oxide UV-C photodetector by MBE

AU - Mukhopadhyay, Partha

AU - Hatipoglu, Isa

AU - Frodason, Ymir K.

AU - Varley, Joel B.

AU - Williams, Martin S.

AU - Hunter, Daniel A.

AU - Gunasekar, Naresh K.

AU - Edwards, Paul R.

AU - Martin, Robert W.

AU - Wu, Feng

AU - Mauze, Akhil

AU - Speck, James S.

AU - Schoenfeld, Winston V.

PY - 2022/9/16

Y1 - 2022/9/16

N2 - We report ultra-high responsivity of epitaxial (SnxGa1-x)2O3 (TGO) Schottky UV-C photodetectors and experimentally identified the source of gain as deep-level defects, supported by first principles calculations. Epitaxial TGO films were grown by plasma-assisted molecular beam epitaxy on (-201) oriented n-type β-Ga2O3 substrates. Fabricated vertical Schottky devices exhibited peak responsivities as high as 3.5×104 A/W at -5V applied bias under 250nm illumination with sharp cutoff shorter than 280nm and fast rise/fall time in milliseconds order. Hyperspectral imaging cathodoluminescence (CL) spectra were examined to find the mid-bandgap defects, the source of this high gain. Irrespective of different tin mole fractions, the TGO epilayer exhibited extra CL peaks at the green band (2.20 eV) not seen in β-Ga2O3 along with enhancement of the blue emission-band (2.64 eV) and suppression of the UV emission-band. Based on hybrid functional calculations of the optical emission expected for defects involving Sn in β-Ga2O3, VGa–Sn complexes are proposed as potential defect origins of the observed green and blue emission-bands. Such complexes behave as acceptors that can efficiently trap photogenerated holes and are predicted to be predominantly responsible for the ultra-high photoconductive gain in the Sn-alloyed Ga2O3 devices by means of thermionic emission and electron tunneling. Regenerating the VGa–Sn defect complexes by optimizing the growth techniques, we have demonstrated a planar Schottky UV-C photodetector of the highest peak responsivity.

AB - We report ultra-high responsivity of epitaxial (SnxGa1-x)2O3 (TGO) Schottky UV-C photodetectors and experimentally identified the source of gain as deep-level defects, supported by first principles calculations. Epitaxial TGO films were grown by plasma-assisted molecular beam epitaxy on (-201) oriented n-type β-Ga2O3 substrates. Fabricated vertical Schottky devices exhibited peak responsivities as high as 3.5×104 A/W at -5V applied bias under 250nm illumination with sharp cutoff shorter than 280nm and fast rise/fall time in milliseconds order. Hyperspectral imaging cathodoluminescence (CL) spectra were examined to find the mid-bandgap defects, the source of this high gain. Irrespective of different tin mole fractions, the TGO epilayer exhibited extra CL peaks at the green band (2.20 eV) not seen in β-Ga2O3 along with enhancement of the blue emission-band (2.64 eV) and suppression of the UV emission-band. Based on hybrid functional calculations of the optical emission expected for defects involving Sn in β-Ga2O3, VGa–Sn complexes are proposed as potential defect origins of the observed green and blue emission-bands. Such complexes behave as acceptors that can efficiently trap photogenerated holes and are predicted to be predominantly responsible for the ultra-high photoconductive gain in the Sn-alloyed Ga2O3 devices by means of thermionic emission and electron tunneling. Regenerating the VGa–Sn defect complexes by optimizing the growth techniques, we have demonstrated a planar Schottky UV-C photodetector of the highest peak responsivity.

KW - defects

KW - ultra-high gain

KW - fast planar tin gallium oxide

KW - UV-C photodetector

KW - responsivity

KW - MBE

U2 - 10.1063/5.0107557

DO - 10.1063/5.0107557

M3 - Article

SN - 0003-6951

VL - 121

JO - Applied Physics Letters

JF - Applied Physics Letters

IS - 11

M1 - 111105

ER -

Role of defects in ultra-high gain in fast planar tin gallium oxide UV-C photodetector by MBE

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Keywords

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Projects

Doctoral Training Partnership 2018-19 University of Strathclyde | Hunter, Daniel

Nanoanalysis for Advanced Materials and Healthcare - EPSRC strategic equipment

University Of Strathclyde - Equipment Account

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