Beyond Blue: New Horizons in Nitrides
Lead Research Organisation:
The University of Manchester
Department Name: Physics and Astronomy
Abstract
Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.
Publications
Barrett R
(2021)
Effect of Micron-scale Photoluminescence Variation on Droop Measurements in InGaN/GaN Quantum Wells
in Journal of Physics: Conference Series
Barrett R
(2024)
Recombination efficiency in c-plane (In,Ga)N/GaN quantum wells: saturation of localisation sites versus Auger-Meitner recombination
in Journal of Physics D: Applied Physics
Binks D
(2022)
Cubic GaN and InGaN/GaN quantum wells
in Applied Physics Reviews
Blenkhorn W
(2018)
Resonant photoluminescence studies of carrier localisation in c-plane InGaN/GaN quantum well structures
in Journal of Physics: Condensed Matter
Christian G
(2016)
Room temperature PL efficiency of InGaN/GaN quantum well structures with prelayers as a function of number of quantum wells
in physica status solidi c
Christian G
(2018)
Recombination from polar InGaN/GaN quantum well structures at high excitation carrier densities
in Physical Review B
| Description | Droop in the efficiency of Nitride LEDs is one of the factors limiting their widespread deployment. We have found that droop occurs in bothy polar and nonpolar quantum well yielding important information non the underlying physics. More recent work on droop has revealed the role of excited localised states. Preliminary work on cubic GaN has shown great promise. We have been awarded a 3 year EPSRC grant to extend the work on cubic material. We have found that there is significant micron-scale variation in the emission efficiency across the QW, and that correlation of the properties of the emission (i.e. peak energy and intensity) are different in green emitting and blue emitting samples, indicating that different recombination mechanisms dominate. This has initiated a PhD project to explore this phenomenon which will try and relate this behaviour to differences in the microstructure. |
| Exploitation Route | This work will help with the understanding of efficiency droop in LEDs. The development of cubic GaN could lead to a new generation of LED materials |
| Sectors | Digital/Communication/Information Technologies (including Software) Electronics Energy |
| Description | Several grant proposals were made to EPSRC, including two Program grant proposals, a proposal for an Industrial Hub and a responsive mode application. The latter was successful. In particular, this grant was used to support some initial measurements on cubic GaN that was included in the successful grant proposal. This subsequent work on cubic GaN has resulted in a patent application, and the formation of a spin out company, Kubos Semiconductors plc (https://www.kubos-semi.com/), who has also licenced the IP associated with the patent application. |
| First Year Of Impact | 2022 |
| Sector | Digital/Communication/Information Technologies (including Software),Electronics,Energy |
| Impact Types | Economic |
| Description | EPSRC Responsive mode |
| Amount | £495,375 (GBP) |
| Funding ID | EP/R010250/1 |
| Organisation | Engineering and Physical Sciences Research Council (EPSRC) |
| Sector | Public |
| Country | United Kingdom |
| Start | 02/2018 |
| End | 12/2020 |
| Title | Data supporting publication entitled "Disentangling the impact of point defect density and carrier localisation enhanced Auger recombination on efficiency droop in (In,Ga)N/GaN quantum wells" |
| Description | Phototluminescence intensity vs carrier density for three samples grown at different temperatures; Phototluminescence transients for these samples; Calculated radiative and Auger recombination coefficients. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2023 |
| Provided To Others? | Yes |
| URL | https://figshare.manchester.ac.uk/articles/dataset/Data_supporting_publication_entitled_Disentanglin... |
| Title | Data supporting publication entitled "Disentangling the impact of point defect density and carrier localisation enhanced Auger recombination on efficiency droop in (In,Ga)N/GaN quantum wells" |
| Description | Phototluminescence intensity vs carrier density for three samples grown at different temperatures; Phototluminescence transients for these samples; Calculated radiative and Auger recombination coefficients. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2023 |
| Provided To Others? | Yes |
| Impact | This data allows the internal quantum efficiency of an InGaN/GaN quantum well to be determined for the first based on atomistic calculations of the radiative and Auger-Meitner recombination coefficients. |
| URL | https://figshare.manchester.ac.uk/articles/dataset/Data_supporting_publication_entitled_Disentanglin... |
| Title | Data supporting review paper on cubic GaN |
| Description | Previously unreported data included in the review paper entitled " Cubic GaN and InGaN / GaN Quantum wells" corresponding to Figure 1 and 5 of that paper. Figure 1 shows the emission wavelengths for quantum well widths between 2 and 10 nm. Figure 5 compares the photoluminescence spectra from epilayers of hexagonal and cubic GaN. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2022 |
| Provided To Others? | Yes |
| Impact | Part of an invited review of cubic GaN |
| URL | https://figshare.manchester.ac.uk/articles/dataset/Data_supporting_review_paper_on_cubic_GaN/1961447... |
| Title | Research data supporting "Local carrier recombination and associated dynamics in m-plane InGaN/GaN quantum wells probed by picosecond cathodoluminescence" |
| Description | Research data in support of the publication "Local carrier recombination and associated dynamics in m-plane InGaN/GaN quantum wells probed by picosecond cathodoluminescence". We have included the original data (tab-separated text files) as plotted for the quantum wells, measured by spatially- and time-resolved cathodoluminescence. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2016 |
| Provided To Others? | Yes |
| Title | Research data supporting "Optical and structural properties of dislocations in InGaN" |
| Description | The figures in this dataset are taken from the associated publication in the Journal of Applied Physics. Data to support figures 2-6 are provided. The following are captions for the figures in the Journal of Applied Physics. Figure 1 - (a) AFM, (b) SEM, and (c) room temperature panchromatic CL taken on the same area of sample B. Figure 2 - (a) AFM, continuous wave (CW) mode CL (b) integrated intensity and (c) peak wavelength, and pulsed mode CL (d) integrated intensity and (e) peak wavelength of the same region of sample D at 300 K (corresponding to the area highlighted in (a)). (f) Streak map taken in the surrounding material, and (g) extracted time decay curve at the spectral position indicated by a square in (g). (The black regions in (e) correspond to pixels where the CL signal was too low to extract accurate value of peak wavelength.) Figure 3 - Room temperature panchromatic CL image of samples (a) A, (b) B, (c) C, and (d) D. In inset of (d), panchromatic CL with brightness and contrast adjusted to reveal CL intensity variation at dislocations. Plots of the (e) intensity ratio and (f) energy shift on the center and on the facet of the V-pit as a function of indium content and dislocation type. Figure 4 - Molecular dynamics results of distribution and length of In-N-In chains in supercells of overall composition 5.5% (a) and 20% (b). (c) Probability of indium atom to be part of multiple atom chain. Figure 5 - Wavelength dependence of (a) decay time tdecay and (b) rise time trise recorded at 15 K on the bright spot of an edge-type dislocation in samples B and D. In background, corresponding time integrated emission spectra (B in violet, and D in blue), and in dotted line, the time response of the system. Figure 6 - Wavelength dependence of the decay time tdecay recorded at 300 K on (a) the surrounding material and (b) bright spot of an edge-type dislocation in sample D, with corresponding time integrated emission spectra and streak map. For direct comparison, the surrounding emission spectrum (the same as in (a)) is added as the dotted line in (b). Figure 7 - ADF-STEM (a,e), dark field TEM images taken under g=11 ¯00 (b,f) and g=0002 (c,g) condition, and EDX mapping of In fraction (d,h) of a V-pit in sample B (a-d) and sample D (e-h). |
| Type Of Material | Database/Collection of data |
| Year Produced | 2023 |
| Provided To Others? | Yes |
| URL | https://www.repository.cam.ac.uk/handle/1810/345547 |
| Description | Collaboration with Tyndall Insitute |
| Organisation | University College Cork |
| Department | Tyndall National Institute |
| Country | Ireland |
| Sector | Academic/University |
| PI Contribution | Input to theory work done at Tyndall Institute |
| Collaborator Contribution | Theoretical input to program |
| Impact | Significant number of papers |
| Start Year | 2009 |
| Description | Cubic GaN |
| Organisation | Anvil Semiconductors |
| Country | United Kingdom |
| Sector | Private |
| PI Contribution | This work is part of a joint program of work between us, the University of Cambridge and Anvil Semiconductors |
| Collaborator Contribution | Anvil Semiconductors provide the substrate materials for our program on cubic GaN |
| Impact | EPSRC responsive mode grant proposal that commenced Feb 2018 |
| Start Year | 2016 |
| Description | Exhibit at Blue Dot |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Public/other audiences |
| Results and Impact | Exhibit at Blue Dot of LED lighting science, Blue Dot is a major science festival held at Jodrell Bank. |
| Year(s) Of Engagement Activity | 2016 |
| Description | University of the 3rd Age |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | Regional |
| Primary Audience | Public/other audiences |
| Results and Impact | Talk to organisation that provides forum for people in retirement to hear about scientific developments |
| Year(s) Of Engagement Activity | 2016 |