Structural Evolution and the Control of Defects in Atomic Layer Deposited HfO2鈥揂l2O3 Stacked Films on GaAs

详细信息    查看全文

• 作者：Yu-Seon Kang ; Dae-Kyoung Kim ; Kwang-Sik Jeong ; Mann-Ho Cho ; Chung Yi Kim ; Kwun-Bum Chung ; Hyoungsub Kim ; Dong-Chan Kim
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2013
• 出版时间：March 27, 2013
• 年：2013
• 卷：5
• 期：6
• 页码：1982-1989
• 全文大小：583K
• 年卷期：v.5,no.6(March 27, 2013)
• ISSN：1944-8252

文摘

The structural characteristics and interfacial reactions of bilayered dielectric stacks of 3 nm HfO₂/2 nm Al₂O₃ and 3 nm Al₂O₃/2 nm HfO₂ on GaAs, prepared by atomic layer deposition (ALD), were examined during film growth and the postannealing process. During the postdeposition annealing (PDA) of the Al₂O₃/HfO₂/GaAs structures at 700 掳C, large amounts of Ga oxides were generated between the Al₂O₃ and HfO₂ films as the result of interfacial reactions between interdiffused oxygen impurities and out-diffused atomic Ga. However, in the case of the HfO₂/Al₂O₃/GaAs structures, the presence of an Al₂O₃ buffer layer effectively blocked the out-diffusion of atomic Ga, thus suppressing the formation of Ga oxide. Microstructural analyses showed that HfO₂ films that were deposited on Al₂O₃/GaAs had completely crystallized during the PDA process, even at 700 掳C, because of the Al₂O₃ diffusion barrier. Capacitance鈥搗oltage measurements showed a relatively large frequency dispersion of the Al₂O₃/HfO₂/GaAs structure in accumulation capacitance compared to the HfO₂/Al₂O₃/GaAs structure due to a higher interface state density. Conductance results revealed that the Al₂O₃ buffer layer on GaAs resulted in a significant reduction in gap states in GaAs. The induced gap state in the Al₂O₃/HfO₂/GaAs structure originated from the out-diffusion of atomic Ga into the HfO₂ film. Density functional theory calculations supported this conclusion.

Keywords:

HfO₂; GaAs; Al₂O₃ passivation; Ga diffusion; interstitial Ga; interfacial reaction