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<p>In this present work, the single crystalline ZnGa<sub>2</sub>O<sub>4</sub> (111) thin film was grown on Nb-doped SrTiO<sub>3</sub> substrates for the first time by pulsed laser deposition techniques with a prospect to fabricate a metal–oxide–semiconductor (MOS) capacitor and investigate its current conduction mechanism as a function of temperature, ranging from room temperature (298&#xa0;K) to high temperature (573&#xa0;K). The X-ray diffraction (XRD) and X-ray photoelectron (XPS) spectroscopy data confirmed the single crystalline nature of ZnGa<sub>2</sub>O<sub>4</sub> (111) with the chemical/electronic states of Zn, Ga, and O corresponding to their respective binding energies. The ultrawide bandgap of ZnGa<sub>2</sub>O<sub>4</sub> was determined to be ~ 5.02&#xa0;eV from UV absorbance spectroscopy, which demonstrates its potential to offer high thermal stability and low leakage current. The sample is subjected to the high-temperature current vs. voltage and voltage vs. capacitance measurements and it exhibits an insignificant hysteresis memory window shift (Δ<i>V</i><sub>fb</sub> ~ 0.0065&#xa0;V) and a small leakage current density (1.1 × 10<sup>–4</sup> A/cm<sup>2</sup> at <i>V</i><sub>g</sub> = 2&#xa0;V and temperature 298&#xa0;K). Additionally, the effective oxide charge density (<i>Q</i><sub>ox</sub>) and interface trapped charge density (<i>D</i><sub>it</sub>) were observed to increase, while the effective dielectric constant (<i>ε</i><sub>r</sub> ~ 9.9) decreased with temperature up to 573&#xa0;K. The detailed current vs. voltage measurements divulged that the Poole–Frankel (PF) emission is the dominant current conduction mechanism in the medium-to-high electric field regions, while Schottky emission (SE) prevails in the low-to-medium field regions. The trapped energy barrier (<i>φ</i><sub>t</sub>) and Schottky barrier height (<i>φ</i><sub>B</sub>) were determined to be ~ 0.52&#xa0;eV and ~ 0.84&#xa0;eV, respectively, from PF and SE emission fitting, which is better than some previous findings of MOS capacitor. Due to the ultrawide bandgap of ZnGa<sub>2</sub>O<sub>4</sub>, the leakage current is less compared to a narrower bandgap semiconductor, which contributes to the efficiency and reliability of ZnGa<sub>2</sub>O<sub>4</sub>/n-SrTiO<sub>3</sub> MOS capacitor in high-temperature environments.</p>

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Charge carrier trapping and current conduction mechanisms in ZnGa2O4/n-SrTiO3 MOS capacitors

  • 期刊论文

  • 发表日期：

    2025年6月27日

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  • Subrata Karmakar,
  • Mahfuz Ahmed Azmain,
  • Alaga Adedayo,
  • Nethala Manikanthababu,
  • Injamamul Hoque Emu,
  • Ravi Droopad,
  • Yihong Chen,
  • Ariful Haque

摘要

In this present work, the single crystalline ZnGa2O4 (111) thin film was grown on Nb-doped SrTiO3 substrates for the first time by pulsed laser deposition techniques with a prospect to fabricate a metal–oxide–semiconductor (MOS) capacitor and investigate its current conduction mechanism as a function of temperature, ranging from room temperature (298 K) to high temperature (573 K). The X-ray diffraction (XRD) and X-ray photoelectron (XPS) spectroscopy data confirmed the single crystalline nature of ZnGa2O4 (111) with the chemical/electronic states of Zn, Ga, and O corresponding to their respective binding energies. The ultrawide bandgap of ZnGa2O4 was determined to be ~ 5.02 eV from UV absorbance spectroscopy, which demonstrates its potential to offer high thermal stability and low leakage current. The sample is subjected to the high-temperature current vs. voltage and voltage vs. capacitance measurements and it exhibits an insignificant hysteresis memory window shift (ΔVfb ~ 0.0065 V) and a small leakage current density (1.1 × 10–4 A/cm2 at Vg = 2 V and temperature 298 K). Additionally, the effective oxide charge density (Qox) and interface trapped charge density (Dit) were observed to increase, while the effective dielectric constant (εr ~ 9.9) decreased with temperature up to 573 K. The detailed current vs. voltage measurements divulged that the Poole–Frankel (PF) emission is the dominant current conduction mechanism in the medium-to-high electric field regions, while Schottky emission (SE) prevails in the low-to-medium field regions. The trapped energy barrier (φt) and Schottky barrier height (φB) were determined to be ~ 0.52 eV and ~ 0.84 eV, respectively, from PF and SE emission fitting, which is better than some previous findings of MOS capacitor. Due to the ultrawide bandgap of ZnGa2O4, the leakage current is less compared to a narrower bandgap semiconductor, which contributes to the efficiency and reliability of ZnGa2O4/n-SrTiO3 MOS capacitor in high-temperature environments.