Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Graphene as Transparent Electrode for Direct Observation of Hole Photoemission from Silicon to Oxide



Rusen Yan, Qin Zhang, Oleg A. Kirillov, Wei Li, James I. Basham, Alexander G. Boosalis, Xuelei X. Liang, Debdeep Jena, Curt A. Richter, Alan C. Seabaugh, David J. Gundlach, Huili G. Xing, Nhan V. Nguyen


The outstanding electrical and optical properties of graphene make it an excellent alternative as a transparent electrode. Here we demonstrate the application of graphene as collector material in internal photoemission (IPE) spectroscopy; enabling the direct observation of both electron and hole injections at a Si/Al2O3 interface and successfully overcoming the long-standing difficulty of detecting holes injected from a semiconductor emitter in IPE measurements. The observed electron and hole barrier heights are 3.5 eV and 4.1 eV, respectively. Thus the bandgap of Al2O3 can be further deduced to be 6.5 eV, in close agreement with the valued obtained by vacuum ultraviolet spectroscopic ellipsometry analysis. The detailed optical modeling of a graphene/Al2O3/Si stack reveals that by using graphene in IPE measurements the carrier injection from the emitter is significantly enhanced and the contribution of carrier injection from the collector electrode is minimal. The method can be readily extended to various IPE test structures for a complete band alignment analysis and interface characterization.
Nano Letters


Graphene, transparent electrode, internal photoemission, semiconductor interface, work function


Yan, R. , Zhang, Q. , Kirillov, O. , Li, W. , Basham, J. , Boosalis, A. , Liang, X. , Jena, D. , Richter, C. , Seabaugh, A. , Gundlach, D. , Xing, H. and Nguyen, N. (2013), Graphene as Transparent Electrode for Direct Observation of Hole Photoemission from Silicon to Oxide, Nano Letters, [online], (Accessed April 19, 2024)
Created March 27, 2013, Updated November 10, 2018