Effect of HMTA concentration on the photodetector performance of hydrothermally synthesized ZnO nanorods
Journal of Alloys and Compounds, cilt.1081, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 1081
- Basım Tarihi: 2026
- Doi Numarası: 10.1016/j.jallcom.2026.191090
- Dergi Adı: Journal of Alloys and Compounds
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Chimica, Compendex, INSPEC, Public Affairs Index, Academic Search Ultimate (EBSCO), Engineering Source (EBSCO)
- Anahtar Kelimeler: Dip-coating, Hexamethylenetetramine (HMTA), Hydrothermal, Photodetector, ZnO nanorod
- Gazi Üniversitesi Adresli: Evet
Özet
ZnO-based nanorods were synthesized on glass substrates via dip-coating and hydrothermal methods, and the influence of hexamethylenetetramine (HMTA) concentration on structural, optical, and photodetector performance was systematically investigated. The HMTA concentration was varied by adjusting the ZnO:HMTA molar ratio as 1:0 (without HMTA), 1:0.3, 1:0.5, 1:1.0, 1:1.5, 1:3.0, and 1:4.0. XRD analyses confirmed the formation of single-phase hexagonal wurtzite ZnO with variations in (002) preferential orientation and crystallinity depending on HMTA concentration, indicating the influence of HMTA on crystal growth behavior. SEM results demonstrated that HMTA strongly controls nanorod morphology, yielding optimized one-dimensional structures with high aspect ratio. Optical measurements revealed a direct band gap ranging from 3.24 to 3.27 eV. Photodetector characterization demonstrated that the device performance strongly depends on HMTA concentration in the visible-light region. The optimized sample (ZH15) exhibited the highest responsivity (9.90 × 10−3A/W) and specific detectivity (2.97 × 109 Jones), together with the fastest response/recovery time of 6.4/7.2 s at 20 mW/cm2 under 5 V bias. Device performance exhibited a concentration-dependent trend, increasing with HMTA content up to an optimal ZnO:HMTA molar ratio, followed by a decline at higher concentrations. This result indicates that an appropriate balance in HMTA is essential, and precise optimization is crucial for achieving high-performance ZnO photodetectors. These findings demonstrate that HMTA optimization is an effective strategy for controlling ZnO nanorod properties and improving visible-light photodetector performance without additional sensitizing materials or complex architectures.