Impact of Resistivity on Electrical Characteristics of Al-Doped ZnO/p Si Heterostructures
Abstract
This study investigates the impact of the resistivity of Aluminum-doped Zinc Oxide (AZO) films on the electrical characteristics of AZO/p-Si heterojunctions. AZO films were deposited using a thermal evaporation technique on p-Si substrates, with varying deposition temperatures to control film morphology and resistivity. Comprehensive current-voltage (I-V) and capacitance-voltage (C-V) measurements were conducted to evaluate the diode performance and interface state dynamics. The results show that samples with higher resistivity, particularly those deposited at room temperature (S1 and S2), exhibit MOS-like behavior, indicating higher concentrations of interface states and defects. In contrast, samples deposited at elevated temperatures (S3, S4, and S5) demonstrate improved diode characteristics, with lower resistivity, enhanced carrier mobility, and better crystalline quality. Mott-Schottky and capacitance-frequency (C-f) analyses further reveal the significant role of interface states in determining the heterojunction's electrical response, especially at lower frequencies where charge trapping dominates. Additionally, photoluminescence (PL) spectra confirm the presence of oxygen vacancies in the AZO films, with strong visible emission observed in S1 and S2, linked to deep-level defect states. This work highlights the critical influence of deposition conditions on the resistivity and performance of AZO films in heterojunction-based optoelectronic devices, offering valuable insights into optimizing material properties for improved device efficiency.