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This project builds on internationally leading research into the growth and study of novel dilute nitride III-N-V alloys at Lancaster and Nottingham and the highly successful recent development of InAs photodiodes and APDs at Sheffield. Lancaster has established unique growth expertise in these mid-infrared materials, while Sheffield has demonstrated high performance InAs APDs (λ<3 µm).

These developments, combined with the expertise of Nottingham in the physics of III-N-Vs, provide an effective platform for developing a new class of high performance mid-infrared materials which are needed for devices operating at wavelengths λ>3 µm, to unlock a wide variety of important applications. MBE growth of dilute nitride InAsN(Sb) alloys at Lancaster has shown that the addition of N reduces the bandgap of InAs and readily enables access to the 3-5 μm spectral range. Meanwhile, Nottingham has demonstrated that, unlike GaAsN, the addition of N to InAs does not markedly degrade the electronic properties of InAsN and that the electron mobility remains relatively high even at N=1% ( ~103 cm2V-1s-1 at 300K).

Lancaster has also shown that the addition of Sb as a surfactant during growth enhances N incorporation and simultaneously increases the photoluminescence intensity at both 4K and room temperature. Lancaster has recently demonstrated InAsN(Sb) growth on GaAs, which has potential for the fabrication of novel light sources, monolithic detector arrays and APDs. Improved carrier confinement and reduced Auger recombination are envisaged for dilute nitride LEDs and lasers. Simpler fabrication, inexpensive manufacturing and near room temperature operation, whilst maintaining monopolar electron ionisation, would be significant advantages for InAsN(Sb) APDs compared with existing cadmium mercury telluride-based technology.

Lancaster University

The Mid-infrared Optoelectronics group in the Physics Department at Lancaster University has unique experience in the epitaxial growth of a variety of ternary, quaternary and pentanary III-V compound semiconductors. Achievements include: lasers and LEDs at 3.3µm for CH4 and 4.2 µm for CO2 detection, demonstration of the first InAsSb quantum dot (QD) LEDs operating at 4 µm; the first mid-IR ring laser operating at 3.3 µm; development of uncooled photodetectors for 3 µm and 4.6 µm; InAsSb/InAs MQW LEDs operating near 4.2 µm at 300 K; InSb QDs and InAsSb type II QDs on InAs. Our group has achieved an internationally leading position in MBE growth of InAsN(Sb) and demonstrated strong mid-infrared photoluminescence from InAsSbN alloys grown on GaAs, and electroluminescence from InAsN(Sb) MQW LEDs.

The University of Nottingham

The Semiconductor Quantum Nanostructures Group in the School of Physics and Astronomy at the University of Nottingham has leading expertise in understanding the quantum behaviour of electrons in semiconductor materials and has made many important contributions in the field of resonant tunnelling. Achievements include the first mapping of the conduction band of Ga(AsN) by magneto-tunnelling spectroscopy and the discovery of novel hot electron transport phenomena. Recent work has demonstrated high electron mobilities and impact ionization phenomena in In(AsN) relevant to the development of novel mid-infrared APDs. The School of Physics and Astronomy (SPA) and the Nanotechnology and Nanoscience Centre in the SPA provide state-of-the-art facilities for structural, optical and electrical studies of semiconductors, including magnetic fields up to 16T.

The University of Sheffield

The Electronics and Electrical Engineering department at the University of Sheffield has a strong track record in the development and optimisation of APDs and photodetectors covering the x-ray to infrared (IR) wavelength range, with funding from EPSRC, TSB, EMRS-DTC, MOD, STFC, ESA and EU FP7. Sheffield has a wealth of experience in measurement and modelling of ionisation coefficients, gain and excess noise, in a wide range of semiconductors such as Si, AlGaAs, InGaAs and InAs, as well as in house characterisation of novel materials such as InGaAsN and GaAsBi and have developed a number of novel techniques for modelling impact ionization.