Effective removal of Si contamination at the GaN regrowth interface through in-situ etching

GaN regrowth plays a pivotal role in the fabrication of GaN-based advanced electronic devices such as current aperture vertical electron transistors and junction field-effect transistors. However, the presence of a high concentration of Si contamination at the regrowth interface often limits device performance. In this study, an in-situ tertiarybutylchloride (TBCl) etching based method was developed. It reduced the interfacial Si contamination to 4.9 x 1011 cm- 2, with the peak Si concentration decreasing to a low level of 2.7 x 1017 cm-3. The efficient removal of interfacial Si resulted in an obvious increase in the breakdown voltage of the regrown PiN diode from 210 V to over 350 V. Moreover, the mechanism was analyzed underlying the Si removal via TBCl etching, and a correlation model was established between the Si contamination level and TBCl etching conditions. The etching temperature, etching rate, and chamber environment can be well controlled to influence the efficiency of TBCl etching in eliminating interfacial Si contamination. These findings provide valuable insights and serve as a reference for the further development of TBCl etching, which holds great potential for manufacturing novel highbreakdown voltage devices with regrowth methods.