Effects of the resistivity of AZO film on the IV and CV characteristics of AZO/p-Si heterojunction

Abstract

Al-doped ZnO (AZO) films with a range of resistivity were deposited on p-Si substrates in oxygen background by varying the laser fluence and substrate temperature using pulsed laser deposition. AZO films with roughness of 4.1–10.3 nm were deposited where the resistivity of the films range from 10−3 Ω cm to 10−1 Ω cm. Ohmic contacts were coated onto the AZO/p-Si heterojunctions to form Au/AZO/p-Si/Al structures and the samples were characterized using I-V and CV measurements. The samples with high resistivity AZO film (~ 10−1 Ω cm) deposited at room temperature exhibited MOS-like characteristics and AZO/p-Si heterojunction with low resistivity AZO films (~ 10−3 Ω cm) deposited at 100 °C to 300 °C showed p-n junction characteristics. Based on the junction formed, the barrier potential, depletion width, depletion capacitance and oxide thickness were deduced. The CV characteristics of the high resistivity samples deposited at room temperature were also shown to be affected by the presence of interface states within the junction.