Comparison between Damage Characteristics of p- and n-GaN Surfaces Etched by Capacitively Coupled Radio Frequency Argon Plasmas

Abstract

Damage characteristics of p-GaN surfaces etched by capacitively coupled radio frequency Ar plasma at various gas pressures have been studied in terms of the ultraviolet (UV) light irradiation effect. The UV light corresponding to Ar II is emitted from the plasma at high gas pressures from 50 to 100 mTorr, whereas no UV light is emitted at a low gas pressure of 10 mTorr. The result of the etched p-GaN surface is compared with that of the etched n-GaN surface. The difference between the results of the p- and n-GaN surfaces depends strongly on the gas pressure. Both the experimental N/Ga ratios at the p- and n-GaN surfaces etched at the low gas pressure decrease with increasing etching time. The decreases in the experimental N/Ga ratios agree with the simulation results that N atoms at the p- and n-GaN surfaces are preferentially removed by Ar+ ions. The morphologies of the p- and n-GaN surfaces etched at the low gas pressure are similar to those of the as-grown surfaces. The damage characteristic of the p-GaN surface induced in the absence of the UV light irradiation also appears at the high gas pressures, although the p-GaN surfaces etched at the high gas pressures are irradiated with the emitted UV light. In contrast, both the experimental N/Ga ratios and morphologies of the n-GaN surfaces etched at the high gas pressures change with increasing etching time. The changes in the n-GaN surfaces probably result from the UV light irradiation.

Surface Analysis of AlGaN Treated with CF₄and Ar Plasma Etching

“…However, in the case of Ar plasma, the AlGaN surface profile was roughened significantly. The AlGaN surface profile etched with Ar plasma was similar to that observed for n-GaN etched with Ar plasma [8][9][10]. This indicates that the change in the AlGaN surface profile was related to UV light irradiation from the Ar plasma.…”

“…However, the mechanism and the related surface damage are not yet known. Previously, we investigated the effect of Ar plasma etching on n-GaN surfaces [8][9][10]. We reported that surface roughening clearly occurs in n-GaN by a synergistic effect between UV light irradiation from the plasma and ion bombardment of the sample surface [8][9][10].…”

Enhanced Current Transport and Injection in Thin-Film Gallium-Nitride Light-Emitting Diodes by Laser-Based Doping

“…These results are comparable to the trends observed in other reports, which have demonstrated that a lower N/Ga ratio leads to the generation of N vacancies. 28,29 N vacancies located at a shallow energy level E D of approximately 25 meV below the conduction band in GaN are well-known for acting as donors. 30 In the presence of Ga vacancies (V Ga ), the low N/Ga ratio may also be explained by the fact that the generation of N vacancies is more pronounced than that of Ga out-diffusion during the LBSD process.…”

Characterization techniques of ion bombardment damage on electronic devices during plasma processing—plasma process-induced damage

“…14) Afterwards, PID has been regarded as critical issues in the fabrication of MOSFETs. In addition, PID to other devices such as memory, 21,22) image sensor, 23,24) power device, 25,26) and optical device 27,28) has been studied over the last four decades, where the degradation of these device parameters was investigated. PID is thus regarded as one of the principal issues in the development of not only leading-edge Si-based devices but also other functional devices in a wide variety of applications.…”