Enhancement of P Diffusion Density in Bulk ZnO for p-type Conductivity

In this paper, we have demonstrated the effect of annealing temperature on the diffusion density of phosphors in Zinc Oxide. The spin on p-dopant was sprayed on ZnO pellets and annealed at different temperatures from 500 to 1000 ̊C with a step of 100 ̊C for one hour using a programmable furnace. The concentration of P was controlled by varying the annealing temperature and the maximum solubility of P (14% At) was achieved at annealing 800 ̊C determined by Energy Dispersive X-Ray Diffraction (EDX) measurements. X-Ray Diffraction (XRD) confirmed the hexagonal structure of ZnO and showed that growth direction was along C-axis. We observed a maximum up shift in (002) plane at annealing temperature 800 ̊C, suggested that P atoms replaced Zn atoms in structure which results in the reduction of lattice constant. Room temperature photoluminescence (PL) spectrum consists of peak at 3.28 eV and related to band edge emission, but samples annealed at 800 and 900 ̊C have an additional donor acceptor pair peak at 3.2 eV. Hot probe method confirmed the p-type conductivity of sample annealed at 800 ̊C.