Barrier Inhomogeneities in n -ZnO/ p -Si Heterojunctions Fabricated with ZnO Nanorods

The p-Si/n-ZnO nanoheterostructures were prepared by the sol–gel and hydrothermal method. The structural characterization carried out by the x-ray diffraction and field emission scanning electron microscope confirms the growth of ZnO nanorods on p-type silicon substrate. The current–voltage (I–V) characteristics of the junction show a rectifying diode-like behavior. The analysis indicates the presence of a high value of series resistance (3.2 KΩ) at the interface. The barrier height extracted from the temperature variation study using the thermionic emission model was of the order of 167.7 meV and the Richardson constant value was of the order of 1.1096E−6 A cm−2 K−2 which is much lower than the standard value, i.e., 32 A cm−2 K−2 for ZnO. Such a discrepancy has been resolved and explained using the Gaussian distribution of barrier heights. The refined value of the barrier height and Richardson constant as calculated from the modified Richardson plot was 1.24 eV and 35.16 A cm−2 K−2, respectively. These are in agreement with the standard reported values.