Enhanced Solar-Blind Photodetector

Schematic representation of the photodetector with Ga2O3 nanocrystals encapsulated in a Al2O3 matrix. (Lobachevsky U.)

Scientists at the Loba­chevsky Univer­sity have been working for several years to develop solar-blind photo­detectors operating in the UV spectral band. 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 the 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 gallium­oxid 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 gallium­oxid 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 nano­crystals by means of ion implan­tation, the basic tech­nology of modern electronics, opens up new possi­bilities for creating solar-blind photo­detectors.

The spectral dependence of photo­response for this photo­detector demon­strates excellent solar-blind ultra­­violet charac­teristics in the wavelength range of 250-270 nm, it also has a high respon­sivity of 50 mA/μW. The dark current of the photo­detector is quite low and amounts to 0.168 mA. The process of creating such a detector involves the synthesis of nano­crystals in a alumina film on silicon by ion implantation. The detector obtained by this method has been realized by the scientists for the first time in the world.

Thus, the joint work of the inter­national team of researchers from the Loba­chevsky Univer­sity, the Indian Institute of Technology Jodhpur and the Indian Institute of Tech­nology Ropar has demon­strated the possi­bility of manu­facturing photo­detectors that cut off solar radiation capable of working in the deep ultra­violet region and possessing the charac­teristics that are not inferior to the existing analogs. “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,” concludes Alexey Mikhaylov. (Source: Lobachevsky Univ.)

Reference: S. Rajamani et al.: Enhanced Solar-Blind Photodetection Performance of Encapsulated Ga2ONanocrystals in Al2OMatrix, IEEE Sens. J. 18, 4046 (2018); DOI: 10.1109/JSEN.2018.2821562

Link: Institute for Physics and Technology, Lobachevsky State University, Nizhni Novgorod, Russia

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