Reducing graphene device variability with yttrium sacrificial layers
Abstract
Graphene technology has made great strides since the material was isolated more than a decade ago. However, despite improvements in growth quality and numerous “hero” devices, challenges of uniformity remain, restricting the large-scale development of graphene-based technologies. Here, we investigate and reduce the variability of graphene transistors by studying the effects of contact metals (with and without a Ti layer), resist, and yttrium (Y) sacrificial layers during the fabrication of hundreds of devices. We find that with optical photolithography, residual resist and process contamination are unavoidable, ultimately limiting the device performance and yield. However, using Y sacrificial layers to isolate the graphene from processing conditions improves the yield (from 73% to 97%), the average device performance (three-fold increase of mobility and 58% lower contact resistance), and the device-to-device variability (standard deviation of Dirac voltage reduced by 20%). In contrast to other sacrificial layer techniques, the removal of the Y sacrificial layer with dilute HCl does not harm surrounding materials, simplifying large-scale graphene fabrication.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- May 29, 2017
- Source ID
- 10.1063/1.4984090
Entities
People
- Enrique A Carrion
- Eric Pop
- Maryann C. Tung
- Ning C. Wang
Organizations
- Air Force Office of Scientific Research
- National Science Foundation
- Stanford University
- University of Illinois Urbana–Champaign