Phase evolution, bandgap engineering and p-type conduction in undoped/N-doped BexZn1−xO alloy epitaxial films

A systematic study of BeZnO alloy epitaxial films on phase evolution, bandgap engineering and p-type conduction was carried out. X-ray diffraction (XRD) and photoluminescence (PL) spectra were used to investigate the detailed phase evolution by Be content variance. A ZnO to amorphous to BeO transition was evidenced with increasing Be content. Moreover, the absorption spectra confirmed the non-practicable of high- and mid-Be content BeZnO as a bandgap engineering material system due to the complicated phase composition and poor crystal quality. But the low-Be content BeZnO is verified a promising starting material for ZnO p-type doping. We demonstrated that the Be incorporation can suppress donor-like Ov in the undoped ZnO host and renders weak p-type conduction. When doped with N, Be can help ZnO capture N atoms more abundantly and stably, which has long been a crucial problem of p-type ZnO. Our research makes a meaningful progress in BeZnO alloy, and provides a better insight into its formation, evolution, band structure and conduction type.