Ghosh, Saptarsi, Frentrup, Martin, Hinz, Alexander M., Pomeroy, James W., Field, Daniel, Wallis, David  ORCID: https://orcid.org/0000-0002-0475-7583, Kuball, Martin and Oliver, Rachel A.
2025.
Buffer-less gallium nitride high electron mobility heterostructures on silicon.
Advanced Materials
37
(9)
, 2413127.
10.1002/adma.202413127
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Abstract
Thick metamorphic buffers are considered indispensable for III-V semiconductor heteroepitaxy on large lattice and thermal-expansion mismatched silicon substrates. However, III-nitride buffers in conventional GaN-on-Si high electron mobility transistors (HEMT) impose a substantial thermal resistance, deteriorating device efficiency and lifetime by throttling heat extraction. To circumvent this, a systematic methodology for the direct growth of GaN after the AlN nucleation layer on six-inch silicon substrates is demonstrated using metal-organic vapor phase epitaxy (MOVPE). Crucial growth-stress modulation to prevent epilayer cracking is achieved even without buffers, and threading dislocation densities comparable to those in buffered structures are realized. The buffer-less design yields a GaN-to-substrate thermal resistance of (11 ± 4) m2 K GW−1, an order of magnitude reduction over conventional GaN-on-Si and one of the lowest on any non-native substrate. As-grown AlGaN/AlN/GaN heterojunctions on this template show a high-quality 2D electron gas (2DEG) whose room-temperature Hall-effect mobility exceeds 2000 cm2 V−1 s−1, rivaling the best-reported values. As further validation, the low-temperature magnetoresistance of this 2DEG shows clear Shubnikov-de-Haas oscillations, a quantum lifetime > 0.180 ps, and tell-tale signatures of spin-splitting. These results could establish a new platform for III-nitrides, potentially enhancing the energy efficiency of power transistors and enabling fundamental investigations into electron dynamics in quasi-2D wide-bandgap systems.
| Item Type: | Article |
|---|---|
| Date Type: | Publication |
| Status: | Published |
| Schools: | Schools > Engineering |
| Publisher: | Wiley |
| ISSN: | 1521-4095 |
| Funders: | Henry Royce Institute, Engineering and Physical Sciences Research Council |
| Date of First Compliant Deposit: | 6 January 2025 |
| Date of Acceptance: | 31 December 2024 |
| Last Modified: | 17 Mar 2025 10:49 |
| URI: | https://orca.cardiff.ac.uk/id/eprint/175019 |
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