Appl. Phys. Lett. 102, 123106 (2013).
Rusen Yan, Qin Zhang, Oleg A. Kirillov, Wei Li, James Basham, Alex Boosalis, Xuelei Liang, Debdeep Jena, Curt A. Richter,Alan C. Seabaugh, David J. Gundlach, Huili G. Xing, N. V. Nguyen.
Semiconductor and Dimensional Metrology Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA and
Department of Electrical Engineering, University of Notre Dame, Notre Dame, Indiana 46556, USA and
Key Laboratory for the Physics and Chemistry of Nano Devices, Peking University, Beijing, China and
Department of Electrical Engineering and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA.
We demonstrate the application of graphene as collector material in internal photoemission(IPE) spectroscopy, which enables direct observation of both electron and hole injections at a Si/Al2O3 interface and overcomes the long-standing difficulty of detecting holes in IPE measurements. The observed electron and hole barrier heights are 3.5 ± 0.1 eV and 4.1 ± 0.1 eV, respectively. Thus, the bandgap of Al2O3 can be deduced to be 6.5 ± 0.2 eV, in good agreement with the value obtained by ellipsometry analysis. Our modeling effort reveals that, by using graphene, the carrier injection from the emitter is significantly enhanced and the contribution from the collector electrode is minimal.
© 2013 American Institute of Physics