Investigation of buffer traps in AlGaN/GaN-on-Si devices by thermally stimulated current spectroscopy and back-gating measurement

• Published in: Applied physics letters Vol. 104; no. 1
• Main Authors: Yang, Shu, Zhou, Chunhua, Jiang, Qimeng, Lu, Jianbiao, Huang, Baoling, Chen, Kevin J.
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 06-01-2014
• Subjects: Aluminum gallium nitrides; Applied physics; Buffers; Deionization; ELECTRON MOBILITY; GALLIUM NITRIDES; HETEROJUNCTIONS; High voltages; Ionization; MATERIALS SCIENCE; Silicon substrates; Spectroscopic analysis; SPECTROSCOPY; Spectrum analysis; Thermally stimulated current; TRAPPING
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4861116

Thermally stimulated current (TSC) spectroscopy and high-voltage back-gating measurement are utilized to study GaN buffer traps specific to AlGaN/GaN lateral heterojunction structures grown on a low-resistivity Si substrate. Three dominating deep-level traps in GaN buffer with activation energies of ΔET1 ∼ 0.54 eV, ΔET2 ∼ 0.65 eV, and ΔET3 ∼ 0.75 eV are extracted from TSC spectroscopy in a vertical GaN-on-Si structure. High back-gate bias applied to the Si substrate could influence the drain current in an AlGaN/GaN-on-Si high-electron-mobility transistor in a way that cannot be explained with a simple field-effect model. By correlating the trap states identified in TSC with the back-gating measurement results, it is proposed that the ionization/deionization of both donor and acceptor traps are responsible for the generation of buffer space charges, which impose additional modulation to the 2DEG channel.