Effects of Interface Disorder on Valley Splitting in SiGe/Si/SiGe Quantum Wells

Zhengping Jiang, Purdue University - Main Campus
Neerav Kharche, Rensselaer Polytechnic Institute
Timothy Boykin, University of Alabama - Huntsville
Gerhard Klimeck, Purdue University - Main Campus

Date of this Version



Applied Physics Letters: Volume 100, Issue 10


Copyright (2012) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters: Volume 100, Issue 10 and may be found at http://dx.doi.org/10.1063/1.3692174. The following article has been submitted to/accepted by Applied Physics Letters. Copyright (2011) Zhengping Jiang, Neerav Kharche, Timothy Boykin, and Gerhard Klimeck. This article is distributed under a Creative Commons Attribution 3.0 Unported License.


A sharp potential barrier at the Si/SiGe interface introduces valley splitting (VS), which lifts the 2-fold valley degeneracy in strained SiGe/Si/SiGe quantum wells (QWs). This work examines in detail the effects of Si/SiGe interface disorder on the VS in an atomistic tight binding approach based on statistical sampling. VS is analyzed as a function of electric field, QW thickness, and simulation domain size. Strong electric fields push the electron wavefunctions into the SiGe buffer and introduce significant VS fluctuations from device to device. A Gedankenexperiment with ordered alloys sheds light on the importance of different bonding configurations on VS. We conclude that a single SiGe band offset and effective mass cannot comprehend the complex Si/SiGe interface interactions that dominate VS.


Nanoscience and Nanotechnology