Solar-blind UV photodetector is based on nanocrystals synthesized by using ion implantation
Scientists at Lobachevsky University (UNN; Nizhnij Novgorod, Russia), the Indian Institute of Technology Jodhpur, and the Indian Institute of Technology Ropar have been working for several years to develop solar-blind photodetectors operating in the UV spectral band.1 In the field of electronic technology, this is an important task, since such devices cut off emission with a wavelength higher than 280 nm, which helps to avoid interference from sunlight and to record UV emission during daylight.
"Due to their high sensitivity to deep UV emission and insensitivity to sunlight, solar-blind photodetectors provide a wide range of important applications including ozone-damage detection, jet-engine monitoring, and flame detection,“ says Alexey Mikhaylov, head of the laboratory at the UNN Physics and Technology Research Institute.
The main materials for creating solar-blind photodetectors are wide-gap semiconductors. Nizhny Novgorod scientists, together with Indian colleagues, consider gallium oxide (Ga2O3) to be a promising semiconductor with a band gap of 4.4-4.9 eV, which cuts off emission with wavelengths higher than 260-280 nm and is capable of detecting emission in the deep ultraviolet range.
The existing methods for Ga2O3 synthesis are quite complicated and poorly compatible with conventional silicon technologies. Besides, the layers obtained by such methods often have many defects. The synthesis of Ga2O3 nanocrystals by means of ion implantation, the basic technology of modern electronics, opens up new possibilities for creating solar-blind photodetectors. The spectral photoresponse for this photodetector shows excellent solar-blind ultraviolet characteristics in the wavelength range of 250-270 nm; the detector also has a high responsivity of 50 mA/μW at 250 nm.
The 0.168 mA dark current of the photodetector is quite low. The process of creating such a detector involves the synthesis of Ga2O3 nanocrystals in a aluminum oxide (Al2O3) film on silicon by ion implantation. A detector fabricated in this way has been realized by the UNN scientists for the first time in the world.
"By producing such photodetectors with the help of ion implantation, it will be possible to use the already existing silicon technologies and to adapt them to the manufacture of new-generation devices," says Mikhaylov.
REFERENCE:
1. Saravanan Rajamani et al., IEEE Sensors Journal (2018); doi: 10.1109/JSEN.2018.2821562.
John Wallace | Senior Technical Editor (1998-2022)
John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.