Impact of Si ion implantation on α-Ga2O3 and β-Ga2O3 lateral MESFET transistors
Abstract
In this work, the feasibility of Si ion-implantation channel engineering in metastable α-Ga2O3 is directly compared with the well-established implantation process used in β-Ga2O3 lateral MESFETs. Identical multi-energy Si implantation schemes (10-200 keV) and thermal annealing conditions were applied to both polymorphs in order to evaluate the compatibility of implantationbased doping with the thermal stability window of α-Ga2O3. For β-Ga2O3, Si implantation followed by high-temperature annealing (900-1100 °C) successfully enabled conductive channel and ohmic contact formation, leading to functional lateral MESFET operation with proper current modulation and saturation behaviour. In contrast, α-Ga2O3 layers grown on m-plane sapphire exhibited a strong limitation associated with their metastable nature. An ALD-deposited Al2O3 capping layer delayed the α→β phase transition up to approximately 700 °C, as confirmed by Xray diffraction analysis. However, electrical measurements revealed no measurable channel conduction after annealing within this temperature range, suggesting that efficient electrical activation of the implanted Si donors was not achieved within the α-Ga₂O₃ thermal stability window. At higher annealing temperatures, where dopant activation would normally be expected, the α-phase underwent complete reconstructive transformation into β-Ga2O3, accompanied by severe structural degradation and suppressed electrical transport. These results demonstrate that the thermal budget required for conventional implantation-based donor activation exceeds the metastability window of α-Ga2O3, even when thermal stabilization layers are employed. The study therefore identifies a fundamental technological limitation for ion-implantation-defined α-Ga2O3 power devices and highlights the need for alternative low-thermal-budget doping and device fabrication strategies.
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BibTeX
@article{vellvehi2026impact,
title = {{Impact of Si ion implantation on α-Ga2O3 and β-Ga2O3 lateral MESFET transistors}},
author = {Aniol Vellvehí and Pierre Gallarday and Edgars Butanovs and Vincent Sallet and José Rebollo and Josep Montserrat and Edvards Strods and Martins Zubkins and Lauris Dimitrocenko and Corine Sartel and Ekaterine Chikoidze and Xavier Perpiña and Miquel Vellvehi and Amador Pérez-Tomás},
journal = {Journal of Alloys and Compounds},
year = {2026},
month = sep,
doi = {10.1016/j.jallcom.2026.191091},
url = {https://hal.science/hal-05778797v1},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Impact of Si ion implantation on α-Ga2O3 and β-Ga2O3 lateral MESFET transistors
AU - Aniol Vellvehí
AU - Pierre Gallarday
AU - Edgars Butanovs
AU - Vincent Sallet
AU - José Rebollo
AU - Josep Montserrat
AU - Edvards Strods
AU - Martins Zubkins
AU - Lauris Dimitrocenko
AU - Corine Sartel
AU - Ekaterine Chikoidze
AU - Xavier Perpiña
AU - Miquel Vellvehi
AU - Amador Pérez-Tomás
PY - 2026
DA - 2026/09/17
JO - Journal of Alloys and Compounds
DO - 10.1016/j.jallcom.2026.191091
UR - https://hal.science/hal-05778797v1
AB - In this work, the feasibility of Si ion-implantation channel engineering in metastable α-Ga2O3 is directly compared with the well-established implantation process used in β-Ga2O3 lateral MESFETs. Identical multi-energy Si implantation schemes (10-200 keV) and thermal annealing conditions were applied to both polymorphs in order to evaluate the compatibility of implantationbased doping with the thermal stability window of α-Ga2O3. For β-Ga2O3, Si implantation followed by high-temperature annealing (900-1100 °C) successfully enabled conductive channel and ohmic contact formation, leading to functional lateral MESFET operation with proper current modulation and saturation behaviour. In contrast, α-Ga2O3 layers grown on m-plane sapphire exhibited a strong limitation associated with their metastable nature. An ALD-deposited Al2O3 capping layer delayed the α→β phase transition up to approximately 700 °C, as confirmed by Xray diffraction analysis. However, electrical measurements revealed no measurable channel conduction after annealing within this temperature range, suggesting that efficient electrical activation of the implanted Si donors was not achieved within the α-Ga₂O₃ thermal stability window. At higher annealing temperatures, where dopant activation would normally be expected, the α-phase underwent complete reconstructive transformation into β-Ga2O3, accompanied by severe structural degradation and suppressed electrical transport. These results demonstrate that the thermal budget required for conventional implantation-based donor activation exceeds the metastability window of α-Ga2O3, even when thermal stabilization layers are employed. The study therefore identifies a fundamental technological limitation for ion-implantation-defined α-Ga2O3 power devices and highlights the need for alternative low-thermal-budget doping and device fabrication strategies.
SN - 0925-8388
ER -