Band offsets and electrical stability characterization of Zr-doped ZnO thin-film transistors with a Gd₂O₃ gate insulator

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• 作者：Hsien-Chin Chiu ; ^{hcchiu@mail.cgu.edu.tw" class="auth_mail} ; Hsiang-Chun Wang ; Yi-Cheng Luo ; Fan-Hsiu Huang ; Hsuan-Ling Kao ; Kuang-Po Hsueh¹
• 关键词：Zr-doped ZnO ; Thin-film transistors (TFTs) ; Low-frequency noise (LFN) ; Valence band offset (VBO)
• 刊名：Microelectronic Engineering
• 出版年：25 April, 2014
• 年：2014
• 卷：118
• 期：Complete
• 页码：20-24
• 全文大小：1105 K

文摘

The performance of zirconium (Zr) doped zinc oxide (ZnO) thin-film transistors (TFTs) grown using an RF co-sputtering method is investigated. This study determines the properties of ZrZnO channel and ZnO channel TFT devices using reactively evaporated Gd₂O₃ as a gate dielectric. The energy discontinuity in the band offsets (螖E_C and 螖E_V) of the Gd₂O₃/ZrZnO and Gd₂O₃/ZnO heterostructures is measured using X-ray photoelectron spectroscopy (XPS). The Gd₂O₃/ZrZnO TFTs exhibit a better conduction band offset (螖E_C = 3.98) and a better electrical stability than Gd₂O₃/ZnO (螖E_C = 3.62) TFTs. The ZrZnO device achieves a threshold voltage (V_TH) of 鈭?.96 V; the sub-threshold slope (S.S) is 0.21 V/decade, the I_on/I_off ratio is 2.46 脳 10⁶, and the field-effect mobility is 1.06 cm²/V-s. In addition, the low-frequency noise (LFN) behavior of ZrZnO and ZnO thin-film transistors is also observed. The fluctuation caused by trapping/detrapping can be reduced by the Zr dopants of the TFT devices. The Hooge鈥檚 parameters are determined to be 伪_H = 1.18 脳 10^鈭? for the ZrZnO TFTs and 伪_H = 5.5 脳 10⁵ for the ZnO TFTs.