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<p>Photodetectors that function in the visible (650&#xa0;nm) and near-infrared (980&#xa0;nm) regions are essential for various optoelectronic applications, including imaging, sensing, and communication. Vanadium dioxide (VO<sub>2</sub>), specifically its monoclinic (M) phase, is a promising candidate due to its narrow bandgap (~ 0.6–0.7&#xa0;eV) and its ability to undergo a reversible semiconductor-to-metal transition (SMT). Although pulsed laser deposition (PLD) allows for the precise synthesis of VO<sub>2</sub> thin films, the effect of film thickness on photodetection performance has not yet been thoroughly examined. This research methodically explores how varied deposition times (0.5–2&#xa0;h.) influence the thickness, crystallinity, SMT characteristics, and photoresponse of VO<sub>2</sub> films. The presence of a Raman peak at 619&#xa0;cm<sup>−1</sup> and an XRD peak at 27.9° corresponding to (011) plane indicate the successful deposition of the VO<sub>2</sub> (M<sub>1</sub>) phase. FESEM micrographs illustrate the typical film growth process, transitioning from a seed layer to grain coalescence as deposition time increases from 0.5 to 2&#xa0;h. The observed temperature-dependent electrical properties confirm SMT in all samples, except the 0.5&#xa0;h. sample, which is likely due to its inadequate thickness that aligns with the XRD and Raman analysis. Photo-IV performance was assessed for the n-VO<sub>2</sub>/p-Si interface. However, the photodetection performance was evaluated at the n-VO<sub>2</sub>/p-Si interface under 980&#xa0;nm illumination with varying power densities, as well as under 650&#xa0;nm light at a constant power density, all conducted at a 5&#xa0;V bias. The n-VO<sub>2</sub>/p-Si interface created with a thicker profile (2&#xa0;h.) demonstrated excellent performance, achieving a responsivity of 3.74 A/W and a quantum efficiency of 474.43%. These results emphasize the significance of thickness in achieving optimal performance for VO<sub>2</sub>-based optoelectronic devices.</p>

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Thickness-dependent structural evolution of VO2 (M1) thin films and photodetection in n-VO2/p-Si heterojunctions

  • 期刊论文

  • 发表日期：

    2026年8月5日

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  • I. Ahmed,
  • A. Ali,
  • K. S. Siow,
  • K. L. Lim,
  • H. Asghar,
  • Z. Akhtar,
  • J. Iqbal,
  • A. Fayyaz,
  • Z. A. Umar

摘要

Photodetectors that function in the visible (650 nm) and near-infrared (980 nm) regions are essential for various optoelectronic applications, including imaging, sensing, and communication. Vanadium dioxide (VO2), specifically its monoclinic (M) phase, is a promising candidate due to its narrow bandgap (~ 0.6–0.7 eV) and its ability to undergo a reversible semiconductor-to-metal transition (SMT). Although pulsed laser deposition (PLD) allows for the precise synthesis of VO2 thin films, the effect of film thickness on photodetection performance has not yet been thoroughly examined. This research methodically explores how varied deposition times (0.5–2 h.) influence the thickness, crystallinity, SMT characteristics, and photoresponse of VO2 films. The presence of a Raman peak at 619 cm−1 and an XRD peak at 27.9° corresponding to (011) plane indicate the successful deposition of the VO2 (M1) phase. FESEM micrographs illustrate the typical film growth process, transitioning from a seed layer to grain coalescence as deposition time increases from 0.5 to 2 h. The observed temperature-dependent electrical properties confirm SMT in all samples, except the 0.5 h. sample, which is likely due to its inadequate thickness that aligns with the XRD and Raman analysis. Photo-IV performance was assessed for the n-VO2/p-Si interface. However, the photodetection performance was evaluated at the n-VO2/p-Si interface under 980 nm illumination with varying power densities, as well as under 650 nm light at a constant power density, all conducted at a 5 V bias. The n-VO2/p-Si interface created with a thicker profile (2 h.) demonstrated excellent performance, achieving a responsivity of 3.74 A/W and a quantum efficiency of 474.43%. These results emphasize the significance of thickness in achieving optimal performance for VO2-based optoelectronic devices.