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<p>This work presents a comprehensive analysis of the eigenenergy structure and intersubband optical transitions of Al<sub>0.3</sub>Ga<sub>0.7</sub>N/AlN cylindrical core–shell quantum dots embedded in an HfO₂ host matrix, aiming to enhance the design and optimization of mid-infrared intersubband optoelectronic devices operating under combined thermal and pressure constraints. The Schrödinger equation is solved using the finite difference method to evaluate confinement energies, dipole matrix elements, nonlinear absorption coefficients, and refractive index changes as functions of structural and environmental parameters. The HfO<sub>2</sub> coating significantly enhances dielectric confinement through polarization-induced band redistribution, increasing the intersubband transition energy ΔE by approximately 25–30% at 300&#xa0;K (137 meV with HfO₂ vs. 106 meV without coating). Over the investigated temperature range (100–400&#xa0;K), ΔE increases from 108 to 141 meV (≈ 0.11 meV/K) for coated dots, indicating a temperature-induced blue-shift. Conversely, increasing pressure from 1 to 4 GPa reduces ΔE from 108 to 63 meV ( ≈ − 15 meV/GPa), producing a pronounced red-shift. In the QD/HfO₂ system, when the incident illumination exceeds 0.15&#xa0;MW/cm², the total absorption coefficient undergoes peak splitting, resulting in two distinct resonant maxima; moreover, the central dip becomes more pronounced as the quantum dot size increases. The combined effects of geometry, dielectric environment, temperature, and pressure provide a controllable platform for tunable mid-infrared intersubband optoelectronic applications.</p>

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Coupled effects of temperature, pressure, and oxidative environment on intersubband spectra of cylindrica AlxGa1−xN/AlN Core–shell quantum dots : Toward tunable intersubband Mid-infrared devices

  • 期刊论文

  • 发表日期：

    2026年5月12日

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  • A. Naifar,
  • K. Hasanirokh

摘要

This work presents a comprehensive analysis of the eigenenergy structure and intersubband optical transitions of Al0.3Ga0.7N/AlN cylindrical core–shell quantum dots embedded in an HfO₂ host matrix, aiming to enhance the design and optimization of mid-infrared intersubband optoelectronic devices operating under combined thermal and pressure constraints. The Schrödinger equation is solved using the finite difference method to evaluate confinement energies, dipole matrix elements, nonlinear absorption coefficients, and refractive index changes as functions of structural and environmental parameters. The HfO2 coating significantly enhances dielectric confinement through polarization-induced band redistribution, increasing the intersubband transition energy ΔE by approximately 25–30% at 300 K (137 meV with HfO₂ vs. 106 meV without coating). Over the investigated temperature range (100–400 K), ΔE increases from 108 to 141 meV (≈ 0.11 meV/K) for coated dots, indicating a temperature-induced blue-shift. Conversely, increasing pressure from 1 to 4 GPa reduces ΔE from 108 to 63 meV ( ≈ − 15 meV/GPa), producing a pronounced red-shift. In the QD/HfO₂ system, when the incident illumination exceeds 0.15 MW/cm², the total absorption coefficient undergoes peak splitting, resulting in two distinct resonant maxima; moreover, the central dip becomes more pronounced as the quantum dot size increases. The combined effects of geometry, dielectric environment, temperature, and pressure provide a controllable platform for tunable mid-infrared intersubband optoelectronic applications.