[1] Univ Sains Malaysia, Sch Phys, Nanooptoelect Res NOR Lab, Gelugor 11800, Pulau Pinang, Malaysia
[2] Univ Teknol MARA, Inst Sci, Ctr Nanosci & Nanotechnol, NANOsciTech Ctr, Shah Alam 40450, Selangor, Malaysia
[3] Univ Malaya, Dept Phys, Kuala Lumpur 50603, Malaysia