Diffusion length of non-equilibrium minority charge carriers in β-Ga2O3 measured by electron beam induced current

E. B. Yakimov; A. Y. Polyakov; N. B. Smirnov; I. V. Shchemerov; Jiancheng Yang; F. Ren; Gwangseok Yang; Jihyun Kim; S. J. Pearton

doi:10.1063/1.5027559

Diffusion length of non-equilibrium minority charge carriers in β-Ga₂O₃ measured by electron beam induced current

E. B. Yakimov, A. Y. Polyakov, N. B. Smirnov, I. V. Shchemerov, Jiancheng Yang, F. Ren, Gwangseok Yang, Jihyun Kim, S. J. Pearton

Department of Chemical and Biological Engineering

Research output: Contribution to journal › Article › peer-review

50 Citations (Scopus)

Abstract

The spatial distribution of electron-hole pair generation in β-Ga₂O₃ as a function of scanning electron microscope (SEM) beam energy has been calculated by a Monte Carlo method. This spatial distribution is then used to obtain the diffusion length of charge carriers in high-quality epitaxial Ga₂O₃ films from the dependence of the electron beam induced current (EBIC) collection efficiency on the accelerating voltage of a SEM. The experimental results show, contrary to earlier theory, that holes are mobile in β-Ga₂O₃ and to a large extent determine the diffusion length of charge carriers. Diffusion lengths in the range 350-400 nm are determined for the as-grown Ga₂O₃, while processes like exposing the samples to proton irradiation essentially halve this value, showing the role of point defects in controlling minority carrier transport. The pitfalls related to using other popular EBIC-based methods assuming a point-like excitation function are demonstrated. Since the point defect type and the concentration in currently available Ga₂O₃ are dependent on the growth method and the doping concentration, accurate methods of diffusion length determination are critical to obtain quantitative comparisons of material quality.

Original language	English
Article number	185704
Journal	Journal of Applied Physics
Volume	123
Issue number	18
DOIs	https://doi.org/10.1063/1.5027559
Publication status	Published - 2018 May 14

Bibliographical note

Funding Information:
The work at NUST MISiS was supported in part by the Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST «MISiS» (R2-2014-055). The work at IMT RAS was partially supported by the State task No. 007-01609-17-01. The work at UF was sponsored by the Department of the Defense, Defense Threat Reduction Agency, HDTRA1-17-1-011, monitored by Jacob Calkins. The work at Korea University was supported by a Korea University grant, LG Innotek-Korea University Nano-Photonics Program, Korea Institute of Energy Technology Evaluation and Planning (KETEP), and the Ministry of Trade, Industry and Energy (MOTIE) of the Republic of Korea (Grant No. 20163010012140).

Publisher Copyright:
© 2018 Author(s).

ASJC Scopus subject areas

Physics and Astronomy(all)

Access to Document

10.1063/1.5027559

Cite this

@article{ba9f8727898e4553a5dc7f68e648a9ac,

title = "Diffusion length of non-equilibrium minority charge carriers in β-Ga2O3 measured by electron beam induced current",

abstract = "The spatial distribution of electron-hole pair generation in β-Ga2O3 as a function of scanning electron microscope (SEM) beam energy has been calculated by a Monte Carlo method. This spatial distribution is then used to obtain the diffusion length of charge carriers in high-quality epitaxial Ga2O3 films from the dependence of the electron beam induced current (EBIC) collection efficiency on the accelerating voltage of a SEM. The experimental results show, contrary to earlier theory, that holes are mobile in β-Ga2O3 and to a large extent determine the diffusion length of charge carriers. Diffusion lengths in the range 350-400 nm are determined for the as-grown Ga2O3, while processes like exposing the samples to proton irradiation essentially halve this value, showing the role of point defects in controlling minority carrier transport. The pitfalls related to using other popular EBIC-based methods assuming a point-like excitation function are demonstrated. Since the point defect type and the concentration in currently available Ga2O3 are dependent on the growth method and the doping concentration, accurate methods of diffusion length determination are critical to obtain quantitative comparisons of material quality.",

author = "Yakimov, {E. B.} and Polyakov, {A. Y.} and Smirnov, {N. B.} and Shchemerov, {I. V.} and Jiancheng Yang and F. Ren and Gwangseok Yang and Jihyun Kim and Pearton, {S. J.}",

note = "Funding Information: The work at NUST MISiS was supported in part by the Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST «MISiS» (R2-2014-055). The work at IMT RAS was partially supported by the State task No. 007-01609-17-01. The work at UF was sponsored by the Department of the Defense, Defense Threat Reduction Agency, HDTRA1-17-1-011, monitored by Jacob Calkins. The work at Korea University was supported by a Korea University grant, LG Innotek-Korea University Nano-Photonics Program, Korea Institute of Energy Technology Evaluation and Planning (KETEP), and the Ministry of Trade, Industry and Energy (MOTIE) of the Republic of Korea (Grant No. 20163010012140). Publisher Copyright: {\textcopyright} 2018 Author(s).",

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T1 - Diffusion length of non-equilibrium minority charge carriers in β-Ga2O3 measured by electron beam induced current

AU - Yakimov, E. B.

AU - Polyakov, A. Y.

AU - Smirnov, N. B.

AU - Shchemerov, I. V.

AU - Yang, Jiancheng

AU - Ren, F.

AU - Yang, Gwangseok

AU - Kim, Jihyun

AU - Pearton, S. J.

N1 - Funding Information: The work at NUST MISiS was supported in part by the Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST «MISiS» (R2-2014-055). The work at IMT RAS was partially supported by the State task No. 007-01609-17-01. The work at UF was sponsored by the Department of the Defense, Defense Threat Reduction Agency, HDTRA1-17-1-011, monitored by Jacob Calkins. The work at Korea University was supported by a Korea University grant, LG Innotek-Korea University Nano-Photonics Program, Korea Institute of Energy Technology Evaluation and Planning (KETEP), and the Ministry of Trade, Industry and Energy (MOTIE) of the Republic of Korea (Grant No. 20163010012140). Publisher Copyright: © 2018 Author(s).

PY - 2018/5/14

Y1 - 2018/5/14

N2 - The spatial distribution of electron-hole pair generation in β-Ga2O3 as a function of scanning electron microscope (SEM) beam energy has been calculated by a Monte Carlo method. This spatial distribution is then used to obtain the diffusion length of charge carriers in high-quality epitaxial Ga2O3 films from the dependence of the electron beam induced current (EBIC) collection efficiency on the accelerating voltage of a SEM. The experimental results show, contrary to earlier theory, that holes are mobile in β-Ga2O3 and to a large extent determine the diffusion length of charge carriers. Diffusion lengths in the range 350-400 nm are determined for the as-grown Ga2O3, while processes like exposing the samples to proton irradiation essentially halve this value, showing the role of point defects in controlling minority carrier transport. The pitfalls related to using other popular EBIC-based methods assuming a point-like excitation function are demonstrated. Since the point defect type and the concentration in currently available Ga2O3 are dependent on the growth method and the doping concentration, accurate methods of diffusion length determination are critical to obtain quantitative comparisons of material quality.

AB - The spatial distribution of electron-hole pair generation in β-Ga2O3 as a function of scanning electron microscope (SEM) beam energy has been calculated by a Monte Carlo method. This spatial distribution is then used to obtain the diffusion length of charge carriers in high-quality epitaxial Ga2O3 films from the dependence of the electron beam induced current (EBIC) collection efficiency on the accelerating voltage of a SEM. The experimental results show, contrary to earlier theory, that holes are mobile in β-Ga2O3 and to a large extent determine the diffusion length of charge carriers. Diffusion lengths in the range 350-400 nm are determined for the as-grown Ga2O3, while processes like exposing the samples to proton irradiation essentially halve this value, showing the role of point defects in controlling minority carrier transport. The pitfalls related to using other popular EBIC-based methods assuming a point-like excitation function are demonstrated. Since the point defect type and the concentration in currently available Ga2O3 are dependent on the growth method and the doping concentration, accurate methods of diffusion length determination are critical to obtain quantitative comparisons of material quality.

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