Preparation of p-type ZnO Films by Alternate Deposition of ZnO and Mg3N2 Films

Films were deposited on a glass substrates heated at 100 °C by alternate deposition of ZnO and Mg3N2 films in an atmosphere of N2 + 0.2% O2. p-type ZnO films with the resistivity of 9.9×103 - 4.5×103 Ωcm were grown by Mg3N2 sputtering for 0.2 s at 50-70 W, whereas an n-type ZnO film was grown for 0.2 s at 90 W. Appearance of the n-type ZnO film is caused by a decrease of O2-partial pressure in an atmosphere. The contraction of the c-axis due to the incorporation of Mg atoms is found in these p-type and n-type ZnO films. When the Mg3N2-depostion period was extended to 5 s, p-type ZnO films were grown in the alternate sputtering at 50 W, whereas only insulator films were grown in the alternate sputtering at 70 W. The optical band gap of the films increases with both a RF power and a period of Mg3N2-deposition.