Integration of RF Circuits with High Speed GaN Switching on Silicon Substrates
Lead Research Organisation:
University of Cambridge
Department Name: Materials Science & Metallurgy
Abstract
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Publications
Chen C
(2024)
Threshold voltage mapping at the nanoscale of GaN-based high electron mobility transistor structures using hyperspectral scanning capacitance microscopy
in Applied Physics Letters
| Title | Supplementary Online Material |
| Description | Supplementary material for Threshold voltage mapping at the nanoscale of GaN-based high electron mobility transistor structures using hyperspectral scanning capacitance microscopy |
| Type Of Art | Image |
| Year Produced | 2024 |
| URL | https://aip.figshare.com/articles/figure/Supplementary_Online_Material/25827700 |
| Description | The work on the growth of nitride high electron mobility transistors on silicon during this award has greatly enhanced our understanding of the mechanisms controlling strain in such devices. This will help us, in future, to develop growth methods which allow the wafer to remain flat (which is important for wafer processing) whilst growing thick layers which tend to introduce strain into the system and bow it into a non-flat shape. We have also increased understanding of the mechanisms which control the film and the substrate conductivity post-growth, which is vital to aid understanding of the device electrical performance. |
| Exploitation Route | The robust growth methods we are developing may be adopted by our industrial partners for commercial devices. Materials grown by these methods are also broadly available to the UK community via the EPSRC National Epitaxy Facility. |
| Sectors | Digital/Communication/Information Technologies (including Software) Electronics |
| Description | Advisory Board of APPG on Semiconductors |
| Geographic Reach | National |
| Policy Influence Type | Participation in a guidance/advisory committee |
| URL | https://publications.parliament.uk/pa/cm/cmallparty/240124/semiconductors.htm |
| Description | DCMS: Compound Semiconductors: Industry & Academia Roundtable |
| Geographic Reach | National |
| Policy Influence Type | Participation in a guidance/advisory committee |
| Description | EPSRC-Innovate UK Semiconductor Technology Roundtable |
| Geographic Reach | National |
| Policy Influence Type | Participation in a guidance/advisory committee |
| Description | EPSRC/Innovate UK Semiconductor Roundtable |
| Geographic Reach | National |
| Policy Influence Type | Contribution to a national consultation/review |
| Description | FCDO UK Semiconductor Sector Visit to Washington DC |
| Geographic Reach | Multiple continents/international |
| Policy Influence Type | Contribution to a national consultation/review |
| Description | FCDO/DSIT Semiconductor Delegation to Washington |
| Geographic Reach | Multiple continents/international |
| Policy Influence Type | Contribution to a national consultation/review |
| Description | Infrastructure for Critical Technologies roundtable with David Smith, Chief Technology Officer |
| Geographic Reach | National |
| Policy Influence Type | Participation in a guidance/advisory committee |
| Description | Institute of Physics / Royal Academy of Engineering Roundtable: UK Semiconductor Challenges and Solutions |
| Geographic Reach | National |
| Policy Influence Type | Contribution to a national consultation/review |
| URL | https://raeng.org.uk/media/2hmbvzke/0402_semi-conductor-report_v2.pdf |
| Description | POST briefing note on semiconductor supply |
| Geographic Reach | National |
| Policy Influence Type | Contribution to a national consultation/review |
| Impact | Availability of a briefing note to policy makers and the public |
| URL | https://post.parliament.uk/research-briefings/post-pn-0721/ |
| Description | RAEng - Quantum Infrastructure Review - Working Group |
| Geographic Reach | National |
| Policy Influence Type | Contribution to a national consultation/review |
| Description | Royal Academy of Engineering: Exploring the UK semiconductor innovation system workshop |
| Geographic Reach | National |
| Policy Influence Type | Contribution to a national consultation/review |
| URL | https://raeng.org.uk/media/rm1hck2o/raeng-exploring-the-uk-semiconductor-innovation-system.pdf |
| Description | eFutures DSIT Semiconductors Project Advisory Group |
| Geographic Reach | National |
| Policy Influence Type | Contribution to a national consultation/review |
| Description | A National Research Facility for Epitaxy |
| Amount | £12,250,477 (GBP) |
| Funding ID | EP/X015300/1 |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 05/2022 |
| End | 06/2027 |
| Description | A National Research Facility for Epitaxy |
| Amount | £12,250,478 (GBP) |
| Funding ID | EP/X015300/1 |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 05/2022 |
| End | 06/2027 |
| Description | Transforming Net Zero with Ultrawide Bandgap Semiconductor Device Technology (REWIRE) |
| Amount | £11,748,845 (GBP) |
| Funding ID | EP/Z531091/1 |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 03/2024 |
| End | 03/2029 |
| Description | Ultrawide Bandgap AlGaN Power Electronics - Transforming Solid-State Circuit Breakers (ULTRAlGaN) |
| Amount | £5,326,504 (GBP) |
| Funding ID | EP/X035360/1 |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 04/2024 |
| End | 04/2029 |
| Title | Research data supporting "Buffer-less Gallium Nitride High Electron Mobility Heterostructures on Silicon" |
| Description | In this work a systematic methodology for the direct growth of GaN after the AlN nucleation layer on 6-inch silicon substrates for high electron mobility transistors (HEMT) applications is demonstrated. The buffer-less design enables crucial growth-stress modulation to prevent epilayer cracking, has similar threading dislocation densities to samples with buffer and a significantly lower GaN-to-substrate thermal resistance. As-grown AlGaN/AlN/GaN HEMT structures on this template exhibit a high-quality 2D electron gas (2DEG) with a room-temperature Hall-effect mobility above 2000 cm2/(V·s). A low-temperature magnetoresistance measurement of the 2DEG shows Shubnikov-de-Haas oscillations, a quantum lifetime > 0.180 ps, as well as tell-tale signatures of spin-splitting. Description of the dataset: File: "Figure 1.zip" contains stress and structural characterisation datasets of GaN/AlN/Si heterostructures - Fig. 1b: stress-thickness curves and mean stress curves with thickness measured during the GaN growth at 200 Torr, 125 Torr, 75Torr, 37.5Torr, and 18 Torr. - Fig. 1c: Final Mean-stresses after 800 nm GaN growth, averaged from multiple growth runs. - Fig. 1d: Wafer-bows at room-temperature for samples grown under different pressures - Fig. 1e: X-ray diffraction (XRD) reciprocal space map of the20-25 AlN reflection. - Fig. 1f: XRD ?-2T scan data showing peaks from the epilayer and substrate - Fig. 1g: XRD F-scans of the 20-21 GaN 400 Si reflections. File: "Figure 2.zip" contains the following dataset - Fig. 2a: Reflectance transients measured during 800 nm GaN growths at 18 Torr and 200 Torr. File: "Figure 3.zip" contains structural characterization data of GaN/AlN/Si heterostructures. - Fig. 3a: ?-Full width at half maximum values (?-FWHM) of the XRD 20-21 and 0002 reflections of GaN layers grown at different growth pressures. - Fig. 3b: Variation of the total and individual dislocation density at the surface of the GaN layers grown at different pressures. File: "Figure 4.zip" contains the thermal characterisation data of GaN/AlN/Si heterostructures - Fig. 4b: Normalised eperimental and modeled thermoreflectance data for the sample for which the GaN layer was grown at 75 Torr - Fig. 4c: Sensitivity analysis with respect to the variation in thickness and the effective thermal conductivity of AlN File: "Figure 5.zip" contains data on the interfacial confinement and room-temperature (RT) transport properties of the 2DEG in GaN/AlN/Si heterostructures - Fig. 5a: Experimental and simulated XRD ?-2T data of the symmetric 004 reflection - Fig. 5b: Simulated conduction band edge and electron concentration across the sample structure showing confinement of the electrons on the GaN side of the interface. - Fig. 5c: Hall-effect measured variation in 2DEG electron density and mobility with barrier composition for designs without and with AlN spacer. File: "Figure 6.zip" contains data on Quantum Hall signatures in the AlGaN/AlN/GaN 2DEG at low temperatures - Fig. 6a: Change in longitudinal magnetoresistance (?Rxx) with increasing magnetic field, B, at 1.8 K. - Fig. 6b: Second derivative of the raw magnetoresistance data (from file Fig. 6a) shows the changing Shubnikov-de-Haas (SdH) amplitudes with magnetic fields. - Fig. 6c: Measured and fitted temperature dependence data of the normalized magnetoresistance peak at a constant magnetic field of 7.05 T. - Fig. 6d: Experimental and fitted Dingle plot data for the oscillation amplitude peaks from Ëœ 5.5 T to Ëœ 13 T, considering an effective mass of m* = 0.210 m0 (obtained from dataset Fig. 6c). |
| Type Of Material | Database/Collection of data |
| Year Produced | 2025 |
| Provided To Others? | Yes |
| URL | https://www.repository.cam.ac.uk/handle/1810/378590 |
| Title | Research data supporting "Nano-cathodoluminescence reveals the effect of electron damage on the optical properties of nitride optoelectronics and the damage threshold" |
| Description | Data corresponding to the figures 1, 2, 4, and 5 in the corresponding manuscript. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2016 |
| Provided To Others? | Yes |
| URL | https://www.repository.cam.ac.uk/handle/1810/260851 |
| Title | Research data supporting "Scanning capacitance microscopy of GaN-based high electron mobility transistor structures: a practical guide" |
| Description | The dataset includes data for the associated article, encompassing the scanning capacitance microscopy (SCM), scanning capacitance spectroscopy (SCS), and mercury CV data related to the GaN-based high electron mobility transistor (HEMT) structures. The SCM and SCS data were acquired using a Bruker Dimension Icon Pro AFM coupled with a Bruker SCM module, saved as '.spm' files viewable with Bruker's NanoScope Analysis software. The mercury CV data was obtained using a mercury probe capacitance-voltage measurement system from Materials Development Corporation, stored as a text file importable to data analysis software like Origin. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2023 |
| Provided To Others? | Yes |
| URL | https://www.repository.cam.ac.uk/handle/1810/355790 |
| Title | Research data supporting "Threshold voltage mapping at the nanoscale of GaN-based high electron mobility transistor structures using hyperspectral scanning capacitance microscopy" |
| Description | The dataset includes data for the associated article, encompassing the atomic force microscopy (AFM, in PeakForce Tapping mode), conventional and hyperspectral scanning capacitance microscopy (SCM), and scanning capacitance spectroscopy (SCS) data related to the GaN-based high electron mobility transistor (HEMT) structures. All the data were acquired using a Bruker Dimension Icon Pro AFM. The AFM was coupled with a Bruker SCM module when collecting the SCM and SCS data. All the data are saved as '.spm' files viewable with Bruker's NanoScope Analysis software. The hyperspectral SCM data can be further analysed using the freeware Hyperspy. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2024 |
| Provided To Others? | Yes |
| URL | https://www.repository.cam.ac.uk/handle/1810/368877 |
| Description | UK Atomic Energy Authority |
| Organisation | UK Atomic Energy Authority |
| Country | United Kingdom |
| Sector | Public |
| PI Contribution | Work on radiation hard transistors |
| Collaborator Contribution | Advice on requriements for radiation hard transistors |
| Impact | Ongoing work |
| Start Year | 2024 |
| Description | Cambridge Festival 2024 |
| Form Of Engagement Activity | Participation in an activity, workshop or similar |
| Part Of Official Scheme? | No |
| Geographic Reach | Local |
| Primary Audience | Public/other audiences |
| Results and Impact | Exhibition on efficient electronics at Cambridge Festival |
| Year(s) Of Engagement Activity | 2024 |
| Description | Industry visits 2024 |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | International |
| Primary Audience | Industry/Business |
| Results and Impact | Muitiple industry visits hosted across 2024 |
| Year(s) Of Engagement Activity | 2024 |
| Description | Royal Academy of Engineering Critical Conversation |
| Form Of Engagement Activity | A formal working group, expert panel or dialogue |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Public/other audiences |
| Results and Impact | In March 2023, semiconductors were listed as the one of 'five technologies that are most critical to the UK' in the government's UK Science and Technology Framework. This online discussion event, hosted by the CEO of the Royal Acdemy of Engineering, explored the latest challenges, and opportunities, with engineers at the forefront of semiconductor research and industry, including Rachel Oliver. A live audience of over 100 watched and it has since been viewed about 300 times on Youtube. As a result of t6his engagement, Rachel was asked to join the eFutures DSIT Semiconductors Project Advisory Group. |
| Year(s) Of Engagement Activity | 2023 |
| URL | https://raeng.org.uk/events/2023/september/semiconductors-a-critical-technology-for-a-critical-time |
| Description | The Context - interview |
| Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Public/other audiences |
| Results and Impact | I was interviewed on "The Context" on the BBC News Channel about the UK Semiconductor Strategy shortly after its publication. |
| Year(s) Of Engagement Activity | 2023 |