1. State Key Laboratory for Superlattices and MicrostructuresInstitute of SemiconductorsChinese Academy of Sciences Beijing 100083 China
2. Center of Materials Science and Optoelectronics EngineeringUniversity of Chinese Academy of Sciences Beijing 100049 China
3. Materials Sciences DivisionLawrence Berkeley National Laboratory Berkeley CA 94720 USA
4. Department of Materials Science and EngineeringUniversity of California Berkeley CA 94720 USA
5. Institute and Hospital of Hepatobiliary SurgeryKey Laboratory of Digital Hepatobiliary Surgery of Chinese PLAChinese PLA Medical SchoolChinese PLA General Hospital Beijing 100853 China