University of Glasgow
Engineering

Semiconductor devices such as laser diodes are ubiquitous in modern society, having enabled the communication and information revolution of the 21st century. Now, emerging applications in quantum technologies, artificial intelligence, and future data infrastructure are pushing contemporary photonic and electronic components to their limits. To fulfil the demands of these applications, next-generation devices will be required to achieve ever-greater output power, speed, and functionality, all whilst minimising power consumption and improving their overall sustainability. However, our ability to realise superior device performance is limited by the current approach to semiconductor crystal growth, which greatly restricts the range of materials that can be used in fabrication and impedes the design of advanced devices. The solution to this performance bottle neck may lie in adopting a radical new paradigm for crystal growth, void-retaining epitaxy (VRE). VRE allows for the precise engineering of nanoscale cavities, or “air-voids”, within device structures, which significantly enhance their optical characteristics by introducing new material properties, such as ultra-low refractive index, that cannot be achieved through the conventional approach. The benefits of VRE are evidenced by the recent demonstration of the photonic crystal surface emitting laser (PCSEL), which now far exceeds the performance of contemporary laser designs in terms of power and spectral purity. As such, VRE is increasingly recognised as being potentially transformative, however the technology is immature, and our knowledge of the fundamental processes involved in growth and void engineering is limited. I will unlock the potential of VRE as the architecture of choice for the next generation of semiconductor devices. By pioneering a new simulation-based methodology, I will move away from the current trial-and-error approach to VRE research, producing a model capable of predicting optimised void geometries and growth conditions. This will not only provide new understanding of the fundamentals of semiconductor growth and void formation, but also significantly reduce the experimental costs of designing new devices. I will also expand the use of VRE beyond PCSELs into application spaces including terahertz, advanced manufacturing, and photonic integration. By providing proof-of-concept examples of next-generation devices I will spearhead VRE as the manufacturing platform of the future.