Effect of the sputtering time on the characteristics of p-SnOx:Na films prepared by the reactive direct current magnetron sputtering method - Hoai Phuong, Pham; Yên Nhi, Pham; Hieu, Bui; Phuong, Nguyen; Trung, Tran; Tuan, Nguyen (VNUHCM Journal of Advanced Research in Natural Sciences, 2022)