Reversed-Polarity iii-nitride sensors for enhanced uv-detection
Smart, enhanced detection of ultraviolet  (UV) radiation will be a key enabling technology for many forthcoming technological revolutions in fields such as industrial processing, space research, defence and medicine. AlGaN alloys with high Al content are the perfect materials for this type of device. By varying their composition, the absorption edge can be precisely controlled across the whole UV range down to wavelengths as short as 200 nm. AlGaN-based photodetectors are fast, with very low dark currents, highly biocompatible, and chemically stable. However, two main problems limit their development: the difficulty in achieving satisfactory p-type doping, and the presence of polarization fields that disrupt the internal electric field and make it difficult the separation of the photo-generated carriers. This project aims to use N-polar AlGaN materials to tackle both problems. This material orientation has proved to favour incorporation of p-type impurities and induce higher electric fields for carrier separation.
Different Metal Organic Vapour Phase Epitaxy (MOVPE) growth conditions will be studied to control the growth of N-polar AlN templates and magnesium doped AlGaN epilayers. Finally, a prototype of solar-blind UV photodetector based on AlGaN/AlGaN heterostructure will be grown, fabricated and fully characterized.
In order to pursue this project, the fellow will carry out the outgoing phase at Nagoya University, Japan, under the join supervision of Prof. Hiroshi Amano and Prof. Markus Pristovsek for a period of 21 months. He will then return to the Tyndall National Institute in Cork, Ireland, for the final 12 months under the supervision of Prof. Peter Parbrook. At the start of this project the candidate will also carry out an initial 3-month secondment period in a company that specialises in sensors to perform a preliminary simulation study and gain better understanding of the industrial requirements for a possible future commercialization of these devices.