GaN based LEDs have enabled a revolution in how we light our homes and businesses. By providing significant improvements in the efficiency of electricity conversion to light, they have allowed a huge reduction in the amount of energy used to light our environment, along with concomitant contributions towards global net zero Carbon targets [1]. To date all commercial GaN LEDs have been based on hexagonal InGaN/GaN quantum wells, however, the hexagonal crystal structure gives rise to inherent limitations on the efficiency of such devices and especially for devices emitting at green, amber and red wavelengths. 

Growth of InGaN/GaN quantum wells instead in the cubic crystal phase, is a promising route to overcome these limitations. Compared to hexagonal-GaN, cubic-GaN benefits from a reduced bandgap and is free of the strong polarization fields that reduces the radiative recombination rate [2]. The cubic phase of GaN however is challenging to produce since it is not the thermodynamically preferred phase.

This presentation will describe our work developing the growth of cubic-GaN layers and on to large area substrates compatible with the low cost, high volume manufacture of long wavelength LEDs. These devices could offer the next revolution in lighting and display technologies.

References

[1] DoE report on “Solid state lighting R&D Opportunities” (2022). https://www.energy.gov/eere/ssl/articles/2022-solid-state-lighting-rd-opportunities

[2] D. J. Binks, P. Dawson, R. A. Oliver, and D. J. Wallis. Appl. Phys. Rev., 9(4), 041309 (2022)