Diffusion of acceptor dopants in monoclinic $β$-Ga$_2$O$_3$
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arXiv
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| Autori principali: | , , , |
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| Natura: | Preprint |
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2025
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| _version_ | 1866911032290574336 |
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| author | Lee, Channyung Scarpulla, Michael A. Ertekin, Elif Varley, Joel B. |
| author_facet | Lee, Channyung Scarpulla, Michael A. Ertekin, Elif Varley, Joel B. |
| contents | $β$-Ga$_2$O$_3$ is a leading ultra-wide band gap semiconductor, but its performance depends on precise control over dopant incorporation and stability. In this work, we use first-principles calculations to systematically assess the diffusion behavior of eight potential deep-level substitutional acceptors (Au, Ca, Co, Cu, Fe, Mg, Mn, and Ni) in $β$-Ga$_2$O$_3$. We consider two key diffusion mechanisms: (i) interstitial diffusion under non-equilibrium conditions relevant to ion implantation, and (ii) trap-limited diffusion (TLD) under near-equilibrium thermal annealing conditions. Our results reveal a strong diffusion anisotropy along the b and c axes, with dopant behavior governed by competition between diffusion and incorporation (or dissociation) activation energies. Under interstitial diffusion, Ca$^{2+}_{\text{i}}$ and Mg$^{2+}_{\text{i}}$ show the most favorable combination of low migration and incorporation barriers, making them promising candidates for efficient doping along the b and c axes, respectively. In contrast, Au$^{+}_{\text{i}}$ diffuses readily, but exhibits an incorporation barrier that exceeds 5 eV, rendering it ineffective as a dopant. From a thermal stability perspective, Co$^{2+}_{\text{i}}$ shows poor activation but high diffusion barriers, which may suppress undesirable migration at elevated temperatures. Under trap-limited diffusion, the dissociation of dopant-host complexes controls mobility. Mg$^{2+}_{\text{i}}$ again emerges as a leading candidate, exhibiting the lowest dissociation barriers along both axes, whereas Co$^{2+}_{\text{i}}$ and Fe$^{2+}_{\text{i}}$ display the highest barriers, suggesting improved dopant retention under thermal stress. Our findings guide dopant selection by balancing activation and thermal stability, essential for robust semi-insulating substrates. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_00906 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Diffusion of acceptor dopants in monoclinic $β$-Ga$_2$O$_3$ Lee, Channyung Scarpulla, Michael A. Ertekin, Elif Varley, Joel B. Materials Science Computational Physics $β$-Ga$_2$O$_3$ is a leading ultra-wide band gap semiconductor, but its performance depends on precise control over dopant incorporation and stability. In this work, we use first-principles calculations to systematically assess the diffusion behavior of eight potential deep-level substitutional acceptors (Au, Ca, Co, Cu, Fe, Mg, Mn, and Ni) in $β$-Ga$_2$O$_3$. We consider two key diffusion mechanisms: (i) interstitial diffusion under non-equilibrium conditions relevant to ion implantation, and (ii) trap-limited diffusion (TLD) under near-equilibrium thermal annealing conditions. Our results reveal a strong diffusion anisotropy along the b and c axes, with dopant behavior governed by competition between diffusion and incorporation (or dissociation) activation energies. Under interstitial diffusion, Ca$^{2+}_{\text{i}}$ and Mg$^{2+}_{\text{i}}$ show the most favorable combination of low migration and incorporation barriers, making them promising candidates for efficient doping along the b and c axes, respectively. In contrast, Au$^{+}_{\text{i}}$ diffuses readily, but exhibits an incorporation barrier that exceeds 5 eV, rendering it ineffective as a dopant. From a thermal stability perspective, Co$^{2+}_{\text{i}}$ shows poor activation but high diffusion barriers, which may suppress undesirable migration at elevated temperatures. Under trap-limited diffusion, the dissociation of dopant-host complexes controls mobility. Mg$^{2+}_{\text{i}}$ again emerges as a leading candidate, exhibiting the lowest dissociation barriers along both axes, whereas Co$^{2+}_{\text{i}}$ and Fe$^{2+}_{\text{i}}$ display the highest barriers, suggesting improved dopant retention under thermal stress. Our findings guide dopant selection by balancing activation and thermal stability, essential for robust semi-insulating substrates. |
| title | Diffusion of acceptor dopants in monoclinic $β$-Ga$_2$O$_3$ |
| topic | Materials Science Computational Physics |
| url | https://arxiv.org/abs/2507.00906 |