Author(s): Fariza, A (Fariza, Aqdas); Ji, XL (Ji, Xiaoli); Gao, YQ (Gao, Yaqi); Ran, JX (Ran, Junxue); Wang, JX (Wang, Junxi); Wei, TB (Wei, Tongbo)

Source: JOURNAL OF APPLIED PHYSICS Volume: 129 Issue: 16 Article Number: 165701 DOI: 10.1063/5.0046560 Published: APR 28 2021

Abstract: For developing p-GaN gate-based enhancement-mode AlGaN/GaN high-electron-mobility transistors, the removal of the p-GaN layer around the gate region is demonstrated by photo-electrochemical etching. The etching behavior of p-GaN/AlGaN/GaN heterostructures along with p-GaN/u-GaN reference samples is investigated in acidic H2SO4/H3PO4 electrolyte solution. The strong oxidant sulfate radical SO4-* formed by H2SO4 stimulates the etching process by either extracting excess electrons from the valence band or providing supplementary holes in the valence band. By optimizing the etching parameters, an average etching rate of 0.27 nm/min with a surface roughness of 2.3 nm is achieved for removing p-GaN from the AlGaN/GaN structure. The etching dynamics of the heterostructure are attributed to the valence-band offset Delta E-v caused by band discontinuity at the p-GaN/AlGaN interface. Under positive anodic bias, the etching process is also controlled by local charge transport between p-GaN and the two-dimensional electron gas channel due to a reduced barrier height.

Accession Number: WOS:000644232900001

ISSN: 0021-8979

eISSN: 1089-7550

Full Text: https://aip.scitation.org/doi/10.1063/5.0046560