Dependence of the NH3 Gas Flow Rate on the Electrical Properties of p-Type ZnO Thin Films Prepared by Using Atomic Layer Epitaxy

p-type ZnO was successfully obtained by using atomic layer epitaxy (ALE) with Zn(C2H5)2 [Diethylzinc, DEZn], H2O, and NH3 as a zinc precursor, an oxidant, and a doping source gas, respectively. An optimum NH3 gas flow rate exists for obtaining p-type ZnO. The lowest electrical resistivity of the p-type ZnO films grown by ALE at the NH3 gas flow rate of 7 sccm is 43.7 Ω⋅cm with a hole concentration of 1.57 × 1017 cm−3. Low-temperature photoluminescence analysis results support that the nitrogen-doped ZnO after annealing is a p-type semiconductor. Also, a model for change from n-type ZnO to p-type ZnO by annealing is proposed.