A unique photoemission method to measure semiconductor heterojunction band offsets

• Published in: Applied physics letters Vol. 102; no. 1; p. 12101
• Main Authors: Zhang, Q., Li, R., Yan, R., Kosel, T., Xing, H. G., Seabaugh, A. C., Xu, K., Kirillov, O. A., Gundlach, D. J., Richter, C. A., Nguyen, N. V.
• Format: Journal Article
• Language: English
• Published: 07-01-2013
• Subjects: Aluminum oxide; Energy bands; Heterojunctions; Indium arsenides; Light absorption; Offsets; Photoemission; Semiconductors
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4772979

We report a unique way to measure the energy band offset of a heterojunction by exploiting the light absorption profile in the heterojunction under visible-ultraviolet internal photoemission. This method was used to determine the band alignment of W/Al2O3/n+InAs/p+Al0.45Ga0.55Sb heterojunctions that are of interest for tunnel field-effect transistors. The barrier heights from the InAs and Al0.45Ga0.55Sb valence band maxima to the Al2O3 conduction band minimum are found to be 3.24 eV plus or minus 0.05 eV and 2.79 eV plus or minus 0.05 eV, respectively, yielding a 0.4 eV plus or minus 0.1 eV offset at the InAs/AlGaSb interface. This approach can readily be applied to characterize a wide range of other semiconductor heterojunctions.