Synthesis of p-type Al–N codoped ZnO films using N2O as a reactive gas by RF magnetron sputtering

Abstract Recent success in the synthesis of p-type ZnO by codoping method results in the fabrication of ZnO-based p–n homojunction, promoting the comprehensive applications in electronics. The ceramic bulk which consists of ZnO–2 wt% Al 2 O 3 is used as the target using a RF magnetron sputtering system in this study with various volume ratios of N 2 O as a reactive gas at the substrate temperature of 500 °C to obtain the Al–N codoped ZnO films and the structure, surface morphologies, electrical properties and transmittance of thin films are analyzed. In this study, all prepared films show a ZnO wurtzite structure with a preferred orientation of (0 0 0 2). As 30% volume ratio N 2 O is introduced, the Al–N codoped ZnO film exhibits the best p-type conductivity with a resistivity of 2.6 ± 0.8 Ω cm, a hole concentration of (2.5 ± 0.2) × 10 17 cm −3 and a Hall mobility of 9.6 ± 0.4 cm 2 /V s. However, excessive N 2 O turns the conduction type from p-type to n-type. With the addition of N 2 O, the absorption edge of the Al–N codoped ZnO film exhibits a red-shift in the spectrum. Additionally, the fabricated ZnO-based homojunction shows a rectifying I – V curves, further demonstrating the successful preparation of the p-type Al–N codoped ZnO film.