Analysis of Temperature-Dependent Electrical Characteristics of n-ZnO Nanowires (NWs)/p-Si Heterojunction Diodes

Abstract

This paper presents the electrical characteristics of n-zinc oxide (ZnO) nanowires (NWs)/p-Si (100) heterojunction diodes fabricated by the oxidation of thermally deposited metallic Zn on Al:ZnO-coated p-Si 〈1 0 0〉 substrates. The electrical parameters of the n-ZnO NWs/p-Si diodes have been estimated by using the room temperature capacitance-voltage (C-V) and temperature-dependent current-voltage (I-V) characteristics of the heterojunction. The carrier concentration of the ZnO NW film and the barrier height of the diode estimated from the C-V characteristics at room temperature are 1.54 × 10 ¹⁵ cm ^-3 and 0.75 eV, respectively. The thermionic emission model was used to analyze the temperature-dependent measured I-V characteristics to estimate the parameters of the diode. The estimated values of the barrier height and ideality factor at room temperature were 0.715 eV and 2.13, respectively. The spatial barrier inhomogeneity was included in the aforementioned analysis by assuming a Gaussian distribution for the barrier height at the n-ZnO NWs/p-Si heterojunction. The Richardson constant A ^* of ZnO was found to be increased from a relatively low value of 9.75 ×10 ^{- 8} A ·cm ^{- 2} ·K ^{- 2} to a more realistic value of 49A ·cm ^{- 2} ·K ^{- 2} after incorporating the barrier inhomogeneity phenomenon in the aforementioned analysis.