Impact of lithium nitrate-induced defects on electrical conduction and 1/f noise in hydrothermally grown ZnO film/nanorod homojunctions

Abstract

We investigate the electrical transport and low-frequency noise (LFN) characteristics of hydrothermally grown n-type ZnO nanorod/nanotextured film homojunctions synthesized via chemical bath deposition with varying Lithium nitrate concentrations. Homojunctions fabricated without Lithium nitrate or with moderate concentrations exhibit stable rectifying behavior, whereas very low or high lithium nitrate levels induce contact-dominated noise or defect-induced instability. Current–voltage analysis reveals asymmetric space-charge-limited current (SCLC) transport: reverse-bias conduction is governed by trap-free SCLC in nanorods, enabling electron mobility extraction, while forward-bias transport is dominated by trap-controlled SCLC in the nanotextured film, consistent with an exponential trap-state distribution. LFN studies show that forward-bias 1/f noise originates from trapping–detrapping in the nanotextured film, whereas reverse-bias noise follows Hooge's mobility fluctuation model. Noise variations with lithium nitrate concentration correlate with changes in trap-state distributions. Overall, this work demonstrates that electrical characterization combined with LFN analysis offers a sensitive and reliable approach for probing defect-mediated electronic disorder in chemically grown oxide semiconductors.