Interlayer-dependent charge transport in FTO/TiO2/CuO/Pt and FTO/SiOx/CuO/Pt heterostructures
Physica B: Condensed Matter, cilt.743, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 743
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.physb.2026.419418
- Dergi Adı: Physica B: Condensed Matter
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Compendex, INSPEC
- Anahtar Kelimeler: CuO, Interlayer engineering, SiOx, Temperature-dependent charge transport, TiO2, Werner–Güttler analysis
- Ankara Üniversitesi Adresli: Evet
Özet
Charge transport was compared in two heterostructures sharing a common fluorine-doped tin oxide (FTO) bottom electrode, copper (II) oxide (CuO) absorber and platinum (Pt) top contacts, with titanium dioxide (TiO2) or silicon oxide (SiOx) as the interlayer: FTO/TiO2/CuO/Pt and FTO/SiOx/CuO/Pt. The oxide layers were deposited by home-built direct-current (DC) magnetron sputtering, and the Pt top contacts were formed by thermal evaporation. Temperature-dependent dark current–voltage (I–V) measurements revealed a clear contrast between the two interlayer configurations. FTO/TiO2/CuO/Pt retained reproducible rectification from 300 to 120 K, with the rectification ratio at ±4 V increasing from 280.81 to 450.33, whereas FTO/SiOx/CuO/Pt showed reproducible rectification only between 300 and 270 K and exhibited substantially higher series resistance. Conventional thermionic-emission and Richardson analyses did not support a homogeneous-barrier description for either structure. For the TiO2-based device, Werner–Güttler analysis consistently resolved two temperature regions, 300–220 K and 200–120 K, with mean barrier heights of 1.192 and 0.720 eV and Gaussian standard deviations of 0.162 and 0.097 V, respectively. The corresponding modified Richardson plots were highly linear, with coefficient-of-determination values (R2) of 0.997 and 0.995, while the SiOx-based device did not satisfy the same Werner–Güttler consistency criteria. High-bias transport was superlinear in both structures, with distinctly different temperature evolution of the power-law slopes. Under approximately −4 V illumination, the SiOx-based structure exhibited directly measured photocurrent enhancement factors of 4.12, 3.63 and 21.0 relative to the TiO2-based structure at 450, 532 and 600 nm, respectively, with a contact-area-normalized responsivity of 8.91 A W−1 at 600 nm. Overall, the two interlayer configurations exhibit pronounced differences in temperature-dependent dark transport and reverse-bias photoresponse.