【Domestic Papers】Study on the effects of Si-doping in molecular beam heteroepitaxial β-Ga₂O₃ films

      Researchers from the Nanjing University have published a dissertation titled "Study on the effects of Si-doping in molecular beam heteroepitaxial β-Ga₂O₃ films " in Journal of Applied Physics.

Abstract

      β-Ga₂O₃, an emerging wide bandgap semiconductor material, holds significant potential for various applications. However, challenges persist in improving the crystal quality and achieving controllable doping of β-Ga₂O₃. In particular, the relationship between these factors and the mechanisms behind them are not fully understood. Molecular beam epitaxy (MBE) is viewed as one of the most sophisticated techniques for growing high-quality crystalline films. It also provides a platform for studying the effects of doping and defects in heteroepitaxial β-Ga₂O₃. In our study, we tackled the issue of Si source passivation during the MBE growth of Si-doped β-Ga₂O₃. We did this by using an electron beam vaporize module, a departure from the traditional Si effusion cell. Our research extensively explores the correlation between Si doping concentration and film properties. These properties include microstructure, morphology, defects, carrier conductivity, and mobility. The results from these investigations are mutually supportive and indicate that a high density of defects in heteroepitaxial β-Ga₂O₃ is the primary reason for the challenges in controllable doping and conductivity. These insights are valuable for the ongoing development and enhancement of β-Ga₂O₃-based device techniques.

FIG. 1. Si concentration in β-Ga₂O₃ films with different currents of EBVM; the inset at upper left shows the Si distribution in the films.

FIG. 2.XRD spectra of β-Ga₂O₃ crystal with different Si doping concentrations.

FIG. 3.The TEM images of β-Ga₂O₃ films with (a) UID; (b) Si-dopped at 4.42 × 10¹⁹ cm⁻³; (c) Si-dopped at 6.11 × 10²⁰ cm⁻³. The corresponding magnified images and FFTs (d)–(f).

Paper Link：https://doi.org/10.1063/5.0190926