1. The Aerospace Corporation, El Segundo, California 90245, USA
2. NanoPower Research Labs, Rochester Institute of Technology, Rochester, New York 14623, USA
3. Electrical and Computer Engineering Department, University of California, Los Angeles, California 90095, USA
4. California NanoSystems Institute, Los Angeles, California 90095, USA
5. IQE, Greensboro, North Carolina 27409, USA