Flat band voltage modulation of AlGaN/GaN MOS capacitor with stacked Al₂O₃/La₂O₃ high dielectric structures

详细信息    查看全文

• 作者：Yu-Hai Chen ^{firefoxchen@163.com" class="auth_mail" title="E-mail the corresponding author} ; Hong-Xia Liu ; ^{hxliu@mail.xidian.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Han-Chen-Xi Xu ; Shu-Long Wang ; Xiao-Jiao Fan ; Lu Zhao ; Xing-yao Feng
• 关键词：Gallium nitride ; Atomic layer deposition ; High-k dielectric ; Flat band voltage ; Dipole layer
• 刊名：Materials Science in Semiconductor Processing
• 出版年：2016
• 出版时间：15 June 2016
• 年：2016
• 卷：48
• 期：Complete
• 页码：9-13
• 全文大小：790 K

文摘

AlGaN/GaN metal-oxide-semiconductor (MOS) capacitor structures using atomic layer deposited high-dielectric-constant (High-k) Al₂O₃/La₂O₃ bilayer films as dielectric have been investigated using high-frequency capacitance-voltage measurement. The stable thickness and uniform surface morphology of the bilayer films with different La/Al deposition cycle ratio (La/Al ratio) were observed after rapid thermal annealing by spectroscopic ellipsometry and atomic force microscopy, respectively. We have found that with a decrease of the La/Al ratio, the dipole layer observed by X-ray photoelectron spectroscopy at Al₂O₃/La₂O₃ interfaces is close to the surface of semiconductor and the flat band voltage shifts to the negative direction. Furthermore, the dramatic drop in dielectric constant of the films as La/Al ratio decrease was caused by the formation of La(OH)₃ in La₂O₃. Finally, the reason for the flat band voltage shifts, which is based on the dielectric constant of Al₂O₃ and La₂O₃ comprising the position of dipole layer in the dielectric films, is proposed.