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Two-Dimensional Materials for Next-Generation Nanoelectronics

Speaker: 
Song-Lin Li (National Institute for Materials Science, Tsukuba,Japan)
Date: 
Wed, 22/05/2013 - 11:00am to 12:00pm
Location: 
S13-M01-11 (Physics Conference Room)
Host: 
Goki Eda
Event Type: 
Seminars

Two-Dimensional Materials for Next-Generation Nanoelectronics:
New Structures and Device Physics

 

Abstract

Two-dimensional layered materials including graphene and molybdenum disulfide (MoS2) have received great attention in atomic field-effect transistor (FET) technology and post-silicon electronics because of their unique atomic-scale thickness and flatness. However, numerous physical and technological issues have to be addressed before practical use. In this talk, we will summarize our efforts in this research filed. The talk consists of two parts: 1) new structures for graphene logic gates and 2) device physics for MoS2 FETs. In the first part, we will introduce the formation of elementary graphene logic gates with a self-adaptive complementary-like architecture, in which the ambipolar nature is used as a benefit rather than a drawback to form logic devices. High-performance voltage inverters with voltage gain large than unity are achieved by using a highly efficient gating technique.[1] The voltage gain can be further enhanced when bilayer graphene is adopted as channel and an energy gap is introduced by perpendicular electric fields.[2] Complementary-like logic NAND and NOR gates are also demonstrated.[3] Physical issues on thickness characterization, carrier injection and scattering mechanisms for MoS2 atomic layers will be addressed in the second part. A rapid and nondestructive layer counting technique for the atomic MoS2 layers is developed by using interference Raman spectroscopy.[4] The carrier injection from metal electrode to ultrathin MoS2 layers is found to be easier than corresponding bulk structures due to lowered effective injection barriers and distinct emission mechanism. Finally, the channel thickness dependent carrier mobility and related carrier scattering mechanism in atomic FETs will be elaborated.[5]

References

[1] S.-L. Li et al, Nano Lett. 2010, 10, 2357;
[2] S.-L. Li et al, ACS Nano 2011, 5, 500;
[3] S.-L. Li et al, Small 2011, 7, 1552;
[4] S.-L. Li et al, ACS Nano 2012, 6, 7381;
[5] S.-L. Li et al, submitted.

Speaker's Bio: Dr. Li received his Ph.D. degree in Condensed Matter Physics in 2009 at the Institute of Physics, Chinese Academy of Sciences, China, where he worked on superconductivity and resistance switching effect in oxide thin films. Afterwards, he moved to the National Institute for Materials Science, Japan for his postdoctoral research. He was a research associate during August, 2009 to September, 2011, and was promoted to ICYS-MANA researcher at the International Center for Young Scientist. Now he focuses on the device physics and electronics in two-dimensional materials.

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