Hwang JD, Lee YH. Studies of NiO/Ag/NiO transparent conducting electrodes on NiO and ZnO Schottky diodes.
Phys Chem Chem Phys 2024;
26:20807-20813. [PMID:
39044484 DOI:
10.1039/d4cp02349h]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2024]
Abstract
A nickel oxide (NiO)/silver (Ag)/NiO (NAN) transparent conducting electrode (TCE) was deposited on NiO and zinc oxide (ZnO) to fabricate Schottky diodes (SDs). The physical and electrical properties of NAN/NiO and NAN/ZnO SDs were studied. In addition, conventional Au/ZnO SDs were fabricated for comparison. The prepared NAN TCE was of n-type, with more than 40% transmittance and a low sheet resistance of 6.5 Ω sq.-1, indicating that NAN is an exceptional TCE. Secondary ion mass spectrometry revealed that Ag atoms diffused into NiO and ZnO in the NAN/NiO and NAN/ZnO SDs, respectively. Owing to the large number of defects on the ZnO surface, the current-voltage (I-V) characteristics of the Au/ZnO SDs followed a linear curve. However, the reduced number of defects and a large barrier height at the NAN/ZnO interface led to a rectifying I-V curve in NAN/ZnO SDs. In contrast, a near homojunction at the NAN/NiO interface caused a linear I-V curve and a large leakage current in NAN/NiO SDs. These issues resulted in a lower ideality factor (5.32) in NAN/ZnO SDs than that in NAN/NiO SDs (15.14). The NAN/ZnO SDs exhibited a higher barrier height (0.91 eV) than the NAN/NiO SDs (0.55 eV). The mechanism of carrier transport was investigated using a ln(I) versus ln(V) plot. The NAN/NiO SDs only exhibited one region of ohmic conduction. However, two distinct regions were observed in the NAN/ZnO SDs. For V ≤ 0.7 V, the space-charge-limited current dominated; however, the diffusion-recombination model controlled carrier transport at V ≥ 0.7 V. Band diagrams were proposed to elucidate the carrier transport mechanism in NAN/NiO and NAN/ZnO SDs.
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