Enhanced Energy Resolution of GaN-on-Sapphire p-i-n Alpha-Particle Detector With Isoelectronic Al-Doped i-GaN Layer

A GaN alpha-particle detector of p-i-n structure was fabricated on a sapphire substrate in this article. The intrinsic layer of the detector was isoelectronic Al-doped GaN with the thickness of 10 μm. The leakage current of the detector remained below 10 pA when the reverse voltage increased from 0 to 40 V, which proved that it had a better crystal quality than the detector based on undoped i-GaN layer, of which the dark current was 10 nA at -40 V. The carrier concentration derived from the 1/ C
²
- V curve was 4.96×10
¹⁴
cm
^-3
, so the i-GaN layer would be fully depleted at -48 V. With the remarkable improvement of electrical properties, the charge collection efficiency (CCE) of the full depleted detector in this article was as high as 99%, while the energy resolution was about 4%. These results reveal the excellent prospect of GaN-on-sapphire for cost-effective alpha-particle detectors.