Ballistic Phosphorene Transistor
Technical Report,01 Sep 2014,31 May 2015
Purdue University West Lafayette United States
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This is the final report for ARO Grant No. W911NF-14-1-0572 entitled Ballistic Phosphorene Transistor as a STIP award for the period 0912014 through 5312015. The ARO program director responsible for the grant is Dr. Joe Qiu. The PI is Prof. Peide Ye of PurdueUniversity. The objective of this project is to explore phosphorene, a name we coined for a 2D atomic layer of black phosphorus BP, which, unlike graphene, can have an inherent and direct bandgap on the order of 1 eV and, unlike MoS2 or other transition-metaldichalcogenides TMDs with strong d-orbital coupling, can have carrier mobility on the order of 104 cm2Vs. Thus, phosphorene can potentially overcome the challenges of all other 2D materials for ultra-scaled thin-body low-power transistor applications there by transforming the electronics industry. Even more, phosphorene and few-layer phosphorene has very unique anisotropic transport properties which we have also first explored in transport. 1,2 In FY15, Professor Yes team investigated unique transport property and explore its potential applications in field-effect transistor at ballistic limit down to 15 nm channel region. His team studied the channel length scaling ofultra-thin phosphorene field-effect transistors FETs, and discuss a scheme for using various contact metals to change transistor characteristics. Through studying transistor behaviors with various channel lengths, the contact resistance can be extracted from the transfer length method TLM. With different contact metals, we find out that the metalBP interface has different Schottky barrier, leading to a significant difference in contact resistance, which is quite different from previous studies of transition metal dichalcogenides TMDs such as MoS2 where Fermi-level is strongly pinned near conduction band edge at metalMoS2 interface. The nature of BP transistors are Schottky barrier FETs, where the on and off states are controlled by tuning the Schottky barriers at the two.