Effect of growth temperature on diode parameters of n-ZnO/p-Si heterojuction diodes grown by atomic layer deposition

n-ZnO/p-Si heterojunctions were grown by atomic layer deposition (ALD) on (100) p-Si substrates at different growth temperatures in the range of ~100–250 °C. The current-voltage characterization of all the heterojunctions showed typical rectifying behavior, a true signature of a p-n junction diode. The diode grown at 100 °C were having significantly lower reverse saturation current (~21 nA) and high rectification factor (~120) compared to those grown at relatively higher temperatures such as 200 or 250 °C. From capacitance-voltage measurements, it was found that the depletion width in the ZnO side of n-ZnO/p-Si diode was maximum (~60 nm) for the diode grown at 100 °C and decreased gradually to ~3 nm for the diodes grown at high temperatures of 250 °C. The electron concentration in ZnO films was found to increase significantly on increasing the growth temperature from ~100 to 250 °C. The junction capacitance also showed an increasing trend with increase in the growth temperature. The variation of diode parameters with growth temperature has been discussed in terms of carrier concentration in ZnO films and associated growth mechanisms of the ALD. Such low temperature grown n-ZnO/p-Si diodes with lower reverse saturation current and large depletion width may be suitable for photo detection applications.