ZnO p–n homojunctions have been fabricated by depositing p-type ZnO thin films using an innovative CVD method on n-type ZnO films produced by conventional D.C sputtering on glass substrates. The individual oxides have been characterized for ohmic contact by current–voltage (I–V) measurements and the semiconducting electrical parameters have been determined by resistivity and Hall effect measurements at room temperature. The formation of ZnO p–n homojunctions has been studied by I–V characteristics at 30, 300 and 400°C. Rectifying nature was observed in the measured I–V curves. The ideality factor, saturation current and the barrier height for the forward bias have been calculated as a function of temperature. The improvement of the junction properties was observed from the decrease in the value of the ideality factor with the increase in temperature. A qualitative energy band diagram of the homojunction has been constructed in order to explain the interband carrier tunneling mechanism.