Codoping effects of the Zn acceptor on the structural characteristics and electrical properties of the Ge donor-doped GaN thin films and its hetero-junction diodes all made by reactive sputtering

Zn acceptor/Ge donor (Zn/Ge)-codoped GaN films with different Zn contents have been deposited on Si substrates at 300 °C and at 90-150 W by RF reactive sputtering technique with cermet targets at the composition atomic ratios of Zn:Ge:(Ga+GaN) at x:0.03:(0.97-x) with x = 0, 0.03, 0.06, and 0.09 and Ga:GaN = 3:7. The films made with such targets were presented in an abbreviated symbol of Zn-x-GeGaN at x = 0, 0.03, 0.06, and 0.09. The morphology, structure, electrical properties, optical property, and hetero-junction diode devices involved in the Zn-x-GeGaN films were thoroughly investigated. The systematic Zn increment into the n-type Zn-0-GeGaN through property evaluation provides the supporting information in studying solid solutioning. Zn-x-GeGaN films converted into p-type semiconductor at x = 0.06 and 0.09. The values of bandgap were in the range of 2.87-3.17 eV with the lower value for the higher Zn content in Zn-x-GeGaN films. The higher RF power led to the faster growth, highly deficient in nitrogen, and a higher Zn atom ratio in the deposited film. The 120W-deposited Zn-0.06-GeGaN film had hole concentration of 7.21 × 1016 cm−3, hole mobility of 39.1 cm2 V−1 s−1, and the electrical conductivity of 0.45 S/cm.