Solar-blind UV photodetector has 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 to develop solar-blind photodetectors operating in the ultraviolet (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. Solar-blind photodetectors provide a wide range of important applications, including ozone-damage detection, jet-engine monitoring, and flame detection. The main materials for creating solar-blind photodetectors are wide-gap semiconductors. The researchers consider gallium oxide (Ga₂O₃) to be a promising semiconductor with a bandgap of 4.4 to 4.9 eV, which cuts off emission with wavelengths higher than 260 to 280 nm and is capable of detecting emission in the deep-UV range.

Existing methods for Ga₂O₃ synthesis are quite complicated and poorly compatible with conventional silicon technologies. In addition, 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 possibilities for creating solar-blind photodetectors. The spectral photoresponse for this photodetector shows excellent solar-blind UV characteristics in the 250 to 270 nm range—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 an 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. Reference: S. Rajamani et al., IEEE Sensors J. (2018); doi:10.1109/jsen.2018.2821562.