Synthesis of p-type Al-N codoped ZnO films using N_2O as a reactive gas by RF magnetron sputtering

摘要

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_2O_3 is used as the target using a RF magnetron sputtering system in this study with various volume ratios of N_2O as a reactive gas at the substrate temperature of 500 ℃ 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_2O 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_2O turns the conduction type from p-type to n-type. With the addition of N_2O, 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.