A research group led by Prof. LONG Shibing from the University of Science and Technology of China (USTC) has developed ultra-sensitive solar-blind ultraviolet photodetectors (SBPDs) for harsh environments using amorphous gallium oxide (AGO). The study title ‘High-Performance Harsh-Environment-Resistant GaOX Solar-Blind Photodetectors via Defect and Doping Engineering’ has been published in Advanced Materials.
Gallium oxide (Ga2O3), with an ultrawide bandgap, is currently regarded as one of the most promising materials for solar-blind photodetectors (SBPDs), which are greatly demanded in harsh environments, such as space exploration. Harsh conditions like overabundant temperature or radiation are often found, demanding a more tolerant substitution for traditional SBPDs. However, the realization of high-performance SBPDs with high tolerance toward harsh environments based on low-cost Gallium oxide material faces great challenges.
Evolution of the gallium oxide films induced by DD engineering (Image by HOU Xiaohu et al.)
Featuring a wide bandgap and heat resistance, gallium oxide is capable of preserving SBPDs’ sensibility. Furthermore, AGO was found with the best optimal performances and compatibility, for it can be easily manufactured and integrated. To compensate for AGO’s shortcomings like low stability and high defect density, the research group designed gallium oxide SBDPs of high tolerance. Defect and doping (DD) engineering was adopted, which included the design of gallium-rich AGO, the annealing for recrystallization and the doping supplementary.
The gallium-rich material was the key to a high-response current and the introduction of doping supplementary, while nitrogen annealing contributed to photo-detecting by measures like partial recrystallization, nano-pores forming, etc. Researchers found that gallium-rich material and nano-pores intensified solar-blind reactive currents, while measures like crystallization, defect reduction and doping supplementary weakened dark currents. The gallium oxide film was toughened by heated nitrogen, enhancing both its photoelectric performances and its tolerance against extreme conditions. SBPDs that went through DD engineering showed remarkable performances such as high resistance. Devices under engineering processes showed superior spectrum-selectiveness in many aspects, along with sharper sensibility under extreme conditions. Gallium oxide detector arrays designed in this way, notably, had their clarity tested by heated solar-blind imaging.
For their comprehensive performances, SBPDs made of gallium oxide are used in the field of ultraviolet detection. Other than devising SBPDs that are inexpensive, sensitive and tolerant, DD engineering also paves the way for designing other photoelectric devices.
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