Effect of Compositional Disorder on Photoionization Cross Section of Interfacial Hydrogenic Impurity in Ga2O3/(Al x Ga1-x )2O3 Core/Shell Quantum Disk

doi:10.16553/j.cnki.issn1000-985x.2025.0213

Abstract

Abstract: In this paper，a novel core/shell quantum disk structure consisting of the fourth ultrawide band gap semiconductors Ga₂O₃ as core layer and （Al _x Ga_1-_x ）₂O₃ as shell layer were presented. The optical intersubband transitions and corresponding photoionization cross sections between the impurity ground state and unbound state，as well as between different impurity bound states in core/shell quantum disk structure were studied by the finite-difference algorithm combined with the variational approach. The influence from the aluminum compositional disorder was taken into account in the numerical simulation for the first time. The results indicate that the compositional disorder effect has negligible impact on the photoionization cross section corresponding the transition from the impurity ground state to the unbound state. In contrast，the photoionization cross sections of transitions between different impurity-bound states exhibit notable change in resonance peaks due to the random potential fluctuation induced by compositional disorder. These findings can provide theoretical guidelines for further exploration of photonic and optoelectronic devices based on ultrawide bandgap materials.

Key words: Ga₂O₃; core/shell quantum disk; compositional disorder; photoionization cross section; binding energy; wave function

CLC Number:

YANG Hao, HA Sihua, ZHU Jun. Effect of Compositional Disorder on Photoionization Cross Section of Interfacial Hydrogenic Impurity in Ga₂O₃/(Al _x Ga_1-_x )₂O₃ Core/Shell Quantum Disk[J]. Journal of Synthetic Crystals, 2026, 55(2): 223-232.

Figures/Tables 8

Fig.1 Schematic diagram of Ga2O3/（Al x Ga1-x ）2O3 core/shell quantum disk in cylindrical coordinate system with “+” at （ρ0，θ0，z0） representing hydrogenic-like impurity. （a） Cross-section view of （ρ，θ） plane in core/shell quantum disk structure；（b） cross-section view of （ρ，z） plane in core/shell quantum disk structure

Table 1 Material parameters used in calculation

Material parameter	Ga₂O₃	（Al _x Ga_1-_x ）₂O₃
Effective mass，m^*［47］	0.28	0.28+0.11x
Band gap，E_g/eV^［35］	4.69	7.03x+4.69（1-x）
Dielectric constant， $ε r$ （ɛ₀）^［48］	10	10

Table 1 Material parameters used in calculation

Material parameter	Ga₂O₃	（Al _x Ga_1-_x ）₂O₃
Effective mass，m^*［47］	0.28	0.28+0.11x
Band gap，E_g/eV^［35］	4.69	7.03x+4.69（1-x）
Dielectric constant， $ε r$ （ɛ₀）^［48］	10	10

Fig.2 xR value of （Al x Ga1-x ）2O3 material with shell thickness of 12 nm in core/shell quantum disk structure

Fig.3 Random potential in core/shell quantum disk structure

Fig.4 Probability density distribution of interfacial impurity states in Ga2O3/（Al x Ga1-x ）2O3 core/shell quantum disk in view Ⅰ （0 nm<ρ<10 nm） under random potentials P1，P2，and P3. （a）~（c） Probability density of ground state Φ00；（d）~（f） probability density of excited state Φ10

Fig.5 Probability density distribution of interfacial impurity states in Ga2O3/（Al x Ga1-x ）2O3 core/shell quantum disk in view Ⅱ （0 nm<ρ<10 nm） under random potentials P1，P2，and P3. （a）~（c） Probability density of ground state Ψ00；（d）~（f） probability density of excited state Ψ01；（g）~（i） probability density of excited state Ψ10；（j）~（l） probability density of excited state Ψ11

Fig.6 Relationship between interfacial impurity binding energy ED and Rc in Ga2O3/（Al x Ga1-x ）2O3 core/shell quantum disk

Fig.7 Relationship between photoionization cross section of interfacial impurity and normalized photon energy in Ga2O3/（Al x Ga1-x ）2O3 core/shell quantum disks under action of random potentials P1，P2，and P3

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Effect of Compositional Disorder on Photoionization Cross Section of Interfacial Hydrogenic Impurity in Ga₂O₃/(Al _x Ga_1-_x )₂O₃ Core/Shell Quantum Disk

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