Enhancing Acceptor-Based Optical Behavior in Phosphorus-Doped ZnO Thin Films Using Boron as Compensating Species

The modulating nature of doping in oxide-based semiconductors has always been an area of interest as it resulted in numerous technological developments. On working with ZnO, the principal challenge faced in its realistic utilization as an optoelectronic material lies in its default n-type of nature due to the presence of native defects. Thus, achieving p-type behavior has been a tedious job, and considerable efforts have been made over the past couple of decades. The incorporation of monodopants has yielded p-type ZnO of unstable reliability, thus spurring research on codoping technology. In present study, we examined the effects of boron implantation time on the structural and optical properties of phosphorus-doped ZnO thin films, with the objective of realizing a material ideal for optoelectronic applications. Furthermore, we investigated the effects of annealing temperature on the behavior of codoped samples. Field emission gun scanning electron microscopy, high-resolution X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence, and conductive atomic force microscopy results evidenced that boron implantation improved the solubility of the acceptor atom (i.e., phosphorus), which in turn improved the films’ acceptor-based optical emission. The various spectral data also indicated the presence and location of boron atoms in the films. Moreover, we realized a shallow acceptor energy level, with the minimum value being 55±0.37 meV from the valence band level. The acceptor-bound exciton peak was observed up to 300 K, indicating the feasibility of room temperature applications of these films. In addition, compared with phosphorus doping, codoping increased the photoluminescence intensity of the acceptor peaks. The codoped samples also exhibited stability in the acceptor behavior with the signature of the acceptor bound peaks observed over the span of 13 months.