1. Department of Materials Science and State Key Laboratory of ASIC and SystemFudan University Shanghai 200433 P. R. China
2. State Key Laboratory of Functional Materials for InformaticsShanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences Shanghai 200050 P. R. China
3. State Key Laboratory of Infrared PhysicsShanghai Institute of Technical PhysicsChinese Academy of Sciences Shanghai 200083 P. R. China