A study on the electrical characteristic of n-ZnO/p-Si heterojunction diode prepared by vacuum coating technique

• Good ZnO thin film was grown over Si substrate by thermal evaporation technique.
• Results confirm good thermal stability of n-ZnO/p-Si heterojunction diode.
• Gaussian distribution to TE model solves the problem of barrier inhomogeneity.
• Modified Richardson constant and mean barrier height is obtained.
• n-ZnO/p-Si heterostructures confirms its suitability for optoelectronic devices.

This article reports fabrication and characterization of n-ZnO/p-Si heterojunction diode using vacuum coating technique. Structural properties, surface morphology and quality of thin film have been studied using XRD, AFM and EDX measurements. The temperature dependent electrical junction properties were investigated by Current–Voltage–Temperature (I–V–T) measurement. Barrier height and ideality factor obtained from I–V measurement has shown the variations of 0.66–0.79 eV and 3.50–3.14 respectively for the temperature range of 25–120 °C. The temperature dependence of series resistance for n-ZnO/p-Si heterojunction diode has also been studied. Temperature dependent I–V measurement gives mean barrier height of 194 meV and Richardson constant of 6.61 × 10−7 A cm−2 K−2, which has shown significant deviation from standard theoretical values for these parameters. Consideration of Gaussian distribution with a standard deviation of σ0 = 0.176 gives modified barrier height and Richardson constant of 1.25 eV and 39.18 A cm−2 K−2 respectively. Value obtained for Richardson constant from modified Richardson plot has shown close relevance with its theoretical value (i.e., 32 A cm−2 K−2) for ZnO. Results confirm that the temperature dependent I–V characteristics of n-ZnO/p-Si heterojunction obey the theory of thermionic emission with Gaussian distribution.