High-Performance p-Type Black Phosphorus Transistor with Scandium Contact

详细信息    查看全文

• 作者：Ling Li ; Michael Engel ; Damon B. Farmer ; Shu-jen Han ; H.-S. Philip Wong
• 刊名：ACS Nano
• 出版年：2016
• 出版时间：April 26, 2016
• 年：2016
• 卷：10
• 期：4
• 页码：4672-4677
• 全文大小：386K
• 年卷期：0
• ISSN：1936-086X

文摘

A record high current density of 580 μA/μm is achieved for long-channel, few-layer black phosphorus transistors with scandium contacts after 400 K vacuum annealing. The annealing effectively improves the on-state current and I_on/I_off ratio by 1 order of magnitude and the subthreshold swing by ∼2.5×, whereas Al₂O₃ capping significantly degrades transistor performances, resulting in 5× lower on-state current and 3× lower I_on/I_off ratio. The influences of moisture on black phosphorus metal contacts are elucidated by analyzing the hysteresis of 3–20 nm thick black phosphorus transistors with scandium and gold contacts under different conditions: as-fabricated, after vacuum annealing, and after Al₂O₃ capping. The optimal black phosphorus film thickness for transistors with scandium contacts is found to be ∼10 nm. Moreover, p-type performance is shown in all transistors with scandium contacts, suggesting that the Fermi level is pinned closer to the valence band regardless of the flake thickness.