[1] Ton Duc Thang Univ, Adv Inst Mat Sci, Lab Appl Phys, Ho Chi Minh City, Vietnam
[2] Ton Duc Thang Univ, Fac Appl Sci, Ho Chi Minh City, Vietnam
[3] Hue Univ, Univ Educ, Phys Dept, Hue 530000, Vietnam
[4] Le Quy Don Tech Univ, Dept Mat Sci & Engn, Hanoi 100000, Vietnam
[5] Duy Tan Univ, Inst Res & Dev, Da Nang 550000, Vietnam
[6] Dong Thap Univ, Div Theoret Phys, Cao Lanh 870000, Vietnam