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Multidimensional validation of low-damage BCl[formula omitted]/Ar atomic layer etching for AlGaN/GaN HEMTs.

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Title: Multidimensional validation of low-damage BCl[formula omitted]/Ar atomic layer etching for AlGaN/GaN HEMTs.
Authors: Gao, Boxuan1 (AUTHOR), Zhu, Jiejie1 (AUTHOR) jjzhu@mail.xidian.edu.cn, Li, Mengdi1 (AUTHOR), Qin, Lingjie1 (AUTHOR), Qian, Yuchen1 (AUTHOR), Huang, Simei1 (AUTHOR), Li, Huilin1 (AUTHOR), Liao, Wanshuo1 (AUTHOR), Ma, Xiaohua1 (AUTHOR)
Source: Materials Science in Semiconductor Processing. Nov2025, Vol. 198, pN.PAG-N.PAG. 1p.
Subjects: Electric distortion, Phonon scattering, Root-mean-squares, Light scattering, Surface analysis
Abstract: This study fabricated recessed-gate AlGaN/GaN HEMTs using atomic layer etching (ALE), with unetched devices and inductively coupled plasma (ICP) etching as controls.Multidimensional characterization comparing surface morphology, electrical properties, trap distributions, and carrier transport dynamics confirmed the low-damage characteristics and optimization capability of ALE. ALE reduces the root mean square (RMS) roughness from 0. 210 nm to 0. 182 nm , while conventional ICP etching drastically increases the RMS to 0. 481 nm , demonstrating ALE's remarkable suppression of etching-induced surface damage. At identical remaining barrier layer thickness, ALE-processed devices exhibit a peak transconductance (g m) of 170. 4 mS/mm , representing a 35.13% enhancement over unetched samples, while ICP etching led to a 14.96% decline. Moreover, ALE reduces the gate leakage current by three orders of magnitude compared to ICP etching, corroborating its low-damage characteristics.TCAD simulations revealed that, ICP etching generates high-density defects at the AlGaN interface, leading to localized electric field distortion and Frenkel–Poole emission. In contrast, ALE effectively inhibits defect generation and alleviated electric field crowding, confirming its intrinsic low-defect properties. Carrier transport analysis further confirmed that the dominant scattering mechanism in both unetched and ALE-processed devices is optical phonon scattering, with mobilities of 1415. 3 cm 2 / V ⋅ s and 1450. 5 cm 2 / V ⋅ s , respectively. For ICP-etched devices, the dominant mechanism transitions to remote charge scattering, causing a sharp mobility drop to 410. 1 cm 2 / V ⋅ s.These results demonstrate low-damage advantages of ALE in morphology, electrical properties, defect control, and mobility optimization, providing both theoretical support and experimental paradigms for precision etching processes and high-performance GaN-based device fabrication. • ALE achieves 0. 182 nm surface roughness much lower than ICP etched devices. • ALE preserves carrier mobility (∼ 1450 cm2/V ⋅ s), while ICP degrades it to 410 cm2/V ⋅ s. • TCAD simulation reveals that atomic layer etching (ALE) effectively inhibits defect-induced electric fields, thereby significantly mitigating Frenkel–Poole emission. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:This study fabricated recessed-gate AlGaN/GaN HEMTs using atomic layer etching (ALE), with unetched devices and inductively coupled plasma (ICP) etching as controls.Multidimensional characterization comparing surface morphology, electrical properties, trap distributions, and carrier transport dynamics confirmed the low-damage characteristics and optimization capability of ALE. ALE reduces the root mean square (RMS) roughness from 0. 210 nm to 0. 182 nm , while conventional ICP etching drastically increases the RMS to 0. 481 nm , demonstrating ALE's remarkable suppression of etching-induced surface damage. At identical remaining barrier layer thickness, ALE-processed devices exhibit a peak transconductance (g m) of 170. 4 mS/mm , representing a 35.13% enhancement over unetched samples, while ICP etching led to a 14.96% decline. Moreover, ALE reduces the gate leakage current by three orders of magnitude compared to ICP etching, corroborating its low-damage characteristics.TCAD simulations revealed that, ICP etching generates high-density defects at the AlGaN interface, leading to localized electric field distortion and Frenkel–Poole emission. In contrast, ALE effectively inhibits defect generation and alleviated electric field crowding, confirming its intrinsic low-defect properties. Carrier transport analysis further confirmed that the dominant scattering mechanism in both unetched and ALE-processed devices is optical phonon scattering, with mobilities of 1415. 3 cm 2 / V ⋅ s and 1450. 5 cm 2 / V ⋅ s , respectively. For ICP-etched devices, the dominant mechanism transitions to remote charge scattering, causing a sharp mobility drop to 410. 1 cm 2 / V ⋅ s.These results demonstrate low-damage advantages of ALE in morphology, electrical properties, defect control, and mobility optimization, providing both theoretical support and experimental paradigms for precision etching processes and high-performance GaN-based device fabrication. • ALE achieves 0. 182 nm surface roughness much lower than ICP etched devices. • ALE preserves carrier mobility (∼ 1450 cm2/V ⋅ s), while ICP degrades it to 410 cm2/V ⋅ s. • TCAD simulation reveals that atomic layer etching (ALE) effectively inhibits defect-induced electric fields, thereby significantly mitigating Frenkel–Poole emission. [ABSTRACT FROM AUTHOR]
ISSN:13698001
DOI:10.1016/j.mssp.2025.109742