1. Materials Department, University of California Santa Barbara, Santa Barbara, California, USA
2. National Renewable Energy Laboratory, Golden, CO, USA
3. Department of Electrical and Computer Engineering, University of California Santa Barbara, Santa Barbara, California, USA
4. Center for Opto-electronic Materials and Devices, Korea Institute of Science and Technology, Seoul, South Korea
5. Integrated Photonics Lab, Computer, Electrical and Mathematical Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
6. Intel Corporation, Santa Clara, CA, USA
7. Department of Materials Science and Engineering, Stanford University, Stanford, California, USA