E-Thesis 78 views 65 downloads
β-Ga₂O₃ For Power Electronic Devices / JACOB ASHER
Swansea University Author: JACOB ASHER
DOI (Published version): 10.23889/SUThesis.71340
Abstract
This thesis explores the development of processes to realise β-Ga2O3-based devices, focusing on etching protocols, dielectric characterisation, and forming ohmic contacts.This work started with developing a photoresist process to enable trench etching for bulk (001) β-Ga2O3 using SiNx hard masks and...
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Swansea University
2025
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| Institution: | Swansea University |
| Degree level: | Doctoral |
| Degree name: | Ph.D |
| Supervisor: | Jennings, M. |
| URI: | https://cronfa.swan.ac.uk/Record/cronfa71340 |
| Abstract: |
This thesis explores the development of processes to realise β-Ga2O3-based devices, focusing on etching protocols, dielectric characterisation, and forming ohmic contacts.This work started with developing a photoresist process to enable trench etching for bulk (001) β-Ga2O3 using SiNx hard masks and dry etching. SiNx was used as the hard mask due to it’s selectivity to β-Ga2O3, and the ease of removal compared to metal masks such as Cr. A photoresist protocol for patterning was developed and tested on Si, α-Al2O3, and β-Ga2O3. These processes are critical for isolating regions in devices like FinFETs and J-FETs, with SiNx demonstrated to be an effective hard mask.The research continued with a study which characterises Al2O3 (ALD) and SiO2 (PECVD) dielectrics on bulk (001) β-Ga2O3 through MIS capacitor fabrication. The effects of prolonged post-metalisation annealing were investigated using CV measurements and the Terman method, this showed a reduction in the hysteresis and interface traps (Dit) after annealing at 200°C. ALD Al2O3 exhibited superior interface quality compared to PECVD SiO2. TEM-EDX analysis revealed potential diffusion at the metal-dielectric interface. There was also an apparent decrease in film thickness after annealing.The final experimental section examines ohmic contacts on β-Ga2O3 using Ti/Al, Ti/Au, Ti/Ag, and Ti/W metalisations. Ti/Au is the most common metal which is used as an ohmic contact, hence deemed to be the most reliable to use as the standard ohmic contact to β-Ga2O3. Ti/Ag had the lowest resistance, however, limited data to agree with this, and so need to be repeated with more reliable experiments.This work lays the foundation for further work to form β-Ga2O3 devices. By investigating processes like etching, dielectric integration, and ohmic contact formation. Finally future work is outlined in the final Chapter, includes optimising material interfaces and refining measurement techniques. |
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| Keywords: |
β-Ga2O3, beta-Ga2O3. GaO, Gallium Oxide, characterisation, MOS, MIS, Metal-OxideSemiconductor, Interface trap density, Dit, Terman, CV, Voltage-Capacitance, Ohmiccontacts, CTLM, IV, Current-Voltage, Barrier height, φb, Power electronic devices |
| College: |
Faculty of Science and Engineering |
| Funders: |
DTP- UKRI |