[1] Hong Kong Polytech Univ, Dept Appl Phys, Kowloon, Hong Kong 999077, Peoples R China
[2] Hong Kong Polytech Univ, Joint Res Ctr Microelect, Kowloon, Hong Kong 999077, Peoples R China
[3] Hong Kong Polytech Univ, Joint Res Ctr Microelect, Kowloon, Hong Kong 999077, Peoples R China
[4] Hong Kong Univ Sci & Technol, Dept Elect & Comp Engn, Kowloon, Hong Kong 999077, Peoples R China