Fast Switching Zincblende GaN LEDs
Lead Research Organisation:
University of Cambridge
Department Name: Materials Science & Metallurgy
Abstract
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Organisations
Publications
Binks D
(2022)
Cubic GaN and InGaN/GaN quantum wells
in Applied Physics Reviews
Dyer D
(2024)
Efficiency droop in zincblende InGaN/GaN quantum wells.
Ghosh S
(2024)
Microstructure and reflectance of porous GaN distributed Bragg reflectors on silicon substrates
in Journal of Applied Physics
Gundimeda A
(2022)
Investigation of wurtzite formation in MOVPE-grown zincblende GaN epilayers on AlxGa1-xN nucleation layers
in Journal of Applied Physics
Gundimeda A
(2022)
Influence of Al x Ga 1-x N nucleation layers on MOVPE-grown zincblende GaN epilayers on 3C-SiC/Si(001)
in Journal of Physics D: Applied Physics
Wade T
(2023)
MOVPE studies of zincblende GaN on 3C-SiC/Si(0 0 1)
in Journal of Crystal Growth
Xiu H
(2023)
Polarity determination of crystal defects in zincblende GaN by aberration-corrected electron microscopy
in Journal of Applied Physics
| Description | We have showed that we can improve the efficiency of cubic GaN LEDs by reducing the density of defects in the material. We have also understood more about how the structure of these materials leads to polarised light emission. |
| Exploitation Route | New LEDs may be used in displays of visible light communications. |
| Sectors | Digital/Communication/Information Technologies (including Software) Electronics |
| Description | We are working directlt with industrial partners to help them take forward zincblende LED technologies to commercialisation |
| First Year Of Impact | 2024 |
| Sector | Digital/Communication/Information Technologies (including Software),Electronics |
| Impact Types | Economic |
| 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 | EPSRC-Innovate UK Semiconductor Technology Roundtable |
| Geographic Reach | National |
| Policy Influence Type | Participation in a guidance/advisory committee |
| 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 | 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 | eFutures DSIT Semiconductors Project Advisory Group |
| Geographic Reach | National |
| Policy Influence Type | Contribution to a national consultation/review |
| Description | Segregation of alloy and dopant atoms at defects in nitride materials |
| Amount | £474,220 (GBP) |
| Funding ID | EP/Y004213/1 |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 02/2024 |
| End | 01/2027 |
| Title | Research data supporting "Microstructure and reflectivity of porous GaN distributed Bragg reflectors on silicon substrates" |
| Description | Distributed Bragg reflectors (DBRs) based on alternating layers of porous and non-porous GaN have been fabricated at the wafer-scale in heteroepitaxial GaN layers grown on silicon substrates. On the Si substrates a 250 nm-thick AlN nucleation layer, a 1700 nm graded AlGaN buffer (from 75 at% Al to 25 at% Al), and a 725 nm non-intentionally doped (NID) GaN buffer layer were grown by MOVPE. Onto this buffer, a 200 nm Si-doped (at 5 × 1018 cm-3) GaN layer was grown to provide a conductive pathway beneath the DBR. Next, a 200 nm NID GaN layer was added, followed by five periods of a latent DBR structure, each consisting of 58 nm highly Si-doped (at 1 × 1019 cm-3) GaN and 41 nm NID GaN. The 150 mm wafer was divided into (1.5 × 2.5) cm2 chips for porosification without lithographic processing. The porosification is achieved via electrochemical etching of highly Si-doped layers with 0.25 M solution of oxalic acid at etching voltages between 3V and 12V. Reflectance spectra were measured using a photoluminescence mapper with a broadband white light source. The measurements were normalised with respect to a pre-calibrated commercially available metallic mirror. Modelling of reflectance spectra was carried out using a transfer matrix model implemented in Microsoft Excel. The following datasets have been deposited in this repository: Figure 3: (a) White light reflectance spectra for samples etched at voltages between 3 V and 12 V. Figure 3: (b) Peak reflectance values plotted against etching bias. Figure 6: Variation in porosity of the layer nearest to the surface with etching bias. Figure 7: (a) Predicted reflectance spectra for samples etched at between 3 V and 12 V, based on the porosity data in Figure 6. Figure 7: (b) Predicted peak reflectance values based on the porosity data in Figure 6 plotted against etching bias. Figure S2: Simulated reflectance spectra for five pair GaN/porous-GaN DBRs with the porous layers having identical porosities between 20% and 70%. Further details of the procedures and the datasets are described in the related publication. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2024 |
| Provided To Others? | Yes |
| URL | https://www.repository.cam.ac.uk/handle/1810/369848 |
| Description | Cambridge Science Festival 2023 |
| Form Of Engagement Activity | Participation in an open day or visit at my research institution |
| Part Of Official Scheme? | No |
| Geographic Reach | Regional |
| Primary Audience | Public/other audiences |
| Results and Impact | About 100 people visited an exhibition at the Department of Materials Science and Metallurgy during the Cambridge Festival. The Cambridge Centre for Gallium Nitride exhibited about LED materials and had very useful conversations. |
| Year(s) Of Engagement Activity | 2023 |
| 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 |