51. Conformal bilayer h-AlN epitaxy on WS2 by ALD with ultralow leakage current.
- Author
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Wang, Shin-Yuan, Chang, Shu-Jui, Huang, Yu-Che, Chih, Jia Hao, Lin, Yu-Chin, Cheng, Chao-Ching, Radu, Iuliana, Hu, Chenming, and Chien, Chao-Hsin
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STRAY currents ,ATOMIC layer deposition ,EPITAXY ,ELECTRONIC equipment ,COMPLEMENTARY metal oxide semiconductors - Abstract
In this work, we develop an ultrathin epitaxial h-AlN as an interfacial layer (IL) between HfO
2 and monolayer WS2 channel by atomic layer deposition (ALD). The growth of ultrathin dielectrics using ALD has been challenging due to the dangling-bond-free surface of 2D materials. By utilizing sub-1 nm h-AlN as an IL and depositing HfO2 high-k dielectric, we were able to form a uniform and atomically flat gate dielectric without voids. The resulting structure exhibits an equivalent oxide thickness as low as 1 nm and ultra-low leakage currents of ∼10−6 A/cm2 . The fabricated top-gate WS2 transistors demonstrate on-off ratios of around 106 and subthreshold swing as low as 93 mV/dec. Furthermore, we have verified the feasibility of using h-AlN IL for a gate-all-around structure. Our work presents a CMOS-compatible low-temperature ALD process for integrating gate dielectrics, offering excellent thickness scalability and uniform coverage around monolayer WS2 nanosheets. The combination of high-quality two-dimensional dielectrics and semiconductors will contribute to the development of future high-performance and low-power electronic devices. [ABSTRACT FROM AUTHOR]- Published
- 2023
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