High performance III-V quantum dot photodetectors for low SWaP infrared devices

Infrared radiation covers a wide electromagnetic spectrum from 0.78 to 1000 um. According to Planck's law, all objects radiate a large portion of infrared radiation at reasonable temperatures, e.g. <6000 K (the surface temperature of the Sun). As a result, infrared photonic systems can be applied to many fields, such as free-space communication, remote sensing, surveillance, spectroscopy, and hazard detection. Many of these applications require both high performance and high operating temperature. The focus of this project is on achieving high performance III-V quantum dot infrared photodetectors for low size, weight, and power (SWaP) devices. High operating temperature (HOT) III-V photodetectors with high quantum efficiency are technically important because the use of mature III-V semiconductors can significantly reduce the fabrication and material cost. More importantly, HOT photodetectors reduce the cooling requirements so that infrared systems can be low SWaP. Despite tremendous progress made in the last two decades, the demand for SWaP infrared photodetectors (particularly for wavelengths >2 micron) becomes increasingly urgent and yet to be met due to intrinsic drawbacks of existing technologies. This work proposes to exploit III-V quantum dot infrared photodetectors for high performance HOT photodetectors. By utilizing new designs and quantum structures, it is possible to improve the quantum efficiency and reduce the dark current, which provide a means of approaching the fundamental detectivity limit. Given that quantum dots are insensitive to defects, the potential of combining silicon electronics and III-V infrared sensing technology also provide a unique opportunity towards mid-infrared Si photonics for sensing and free-space communication, which leverages the near-infrared Si photonics developed for optical integrated circuits and data communication.

A large amount of information exists outside the electromagnetic spectrum visible to human beings. Particularly photodetection in the infrared spectral region can generate much useful information that can be used in many applications, such as industrial production control, chemical sensing, clinic imaging, environmental monitoring, defence, astronomy, and hazard detection. Infrared photodetectors with small size, low cost, and low power consumption, play a critical role in the wide deployment of infrared photonics systems and potentially change our life styles. This research project aims to impact upon both defence and civil sections by developing new infrared detection technology.

The main economic impact of the proposed project is a lowered barrier to entry for infrared technologies in civil sectors. Compact and low cost infrared devices and systems provides a technology platform for developing many applications in sensing and automation. For instance, smart self-diagnostics and hand-hold detection devices/systems can be implemented based on the new but cheap light sensing technology far beyond the visible spectrum. it is anticipated that the outcomes of this project can facilitate creation of spin-off companies and further boosting economics.

The main societal impact of this proposed project will be enhanced capability for resilient nation and national wellbeing. Infrared sensing technology plays a critical role in national defence and security. The outcome of this project can enable early detection of hazards and protect the UK from internal and external threats. On the other hand, SWaP infrared technology will have a significant impact on the healthcare, environment, and firefighting and rescuing. Infrared photodetectors will enable non-contact and low-risk medical diagnosis techniques. Self-diagnosis gadget can be made available in market for earlier diagnosis of health problems with small and low-cost infrared systems instead of bulky and expensive ones. Systems for pollution control and climate monitoring can also be developed to reduce the involvement of manpower, particularly in remote and hazardous areas. Portable search and rescue equipment with improved sensitivity can also be developed to help to reduce the time to locate live victims in nature disasters or other catastrophic events when time is of the essence.

Overall, this project addresses the issues related to currently available technologies, and will offer to a wide range of communities in UK, including defence, healthcare, and security, a small, light-weighted and low power infrared photodetector technology. It is therefore very timely to devote efforts in this area and to exploit the next generation infrared technology that can be widely deployed in the next 10-50 years as well as train researcher and students in this field. The significant advantages of low size, weight, and power infrared systems will provide the UK government and commercial companies with an opportunity to identify strong niches in this global market in which it can effectively compete.