Electronic properties of the interface between Si and sputter deposited indium-tin oxide

We have investigated electronic properties of the interface between p-type Si and indium-tin oxide (ITO) films grown by magnetron sputtering. Current–voltage (I–V) and capacitance–voltage (C–V) measurements and deep level transient spectroscopy (DLTS) have been employed. The behaviour of the I–V and C–V characteristics for the ITO/p-Si junctions is correlated to the presence of interfacial states observed by DLTS. Thermal stability of the interfacial states is studied in the temperature range 100–400 °C. For the structures deposited at room temperature, the I–V characteristics show a diode-like behaviour with rectification of about three orders of magnitude. However, the I–V curve cannot be described within the thermionic emission–diffusion approximation. C–V measurements reveal non-linearity in the 1/C2 dependence on V in the near-interface region, indicating the presence of carrier traps. Hole traps have been indeed observed by DLTS and exhibit an activation energy of 0.3 eV with a physical location near the p-Si/ITO interface. Heat treatments in the temperature range 100–400 °C result in annealing of these hole traps and improvement of the I–V and C–V characteristics. The correlation between the electrical properties of the Si/ITO heterojunction and the presence of the electronic states is discussed.