Vertical GaN-on-GaN Schottky Diodes as α-Particle Radiation Sensors

• Published in: Micromachines (Basel) Vol. 11; no. 5; p. 519
• Main Authors: Sandupatla, Abhinay, Arulkumaran, Subramaniam, Ing, Ng Geok, Nitta, Shugo, Kennedy, John, Amano, Hiroshi
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 20.05.2020; MDPI
• Subjects: Breakdown; Carrier density; Charge density; Charge efficiency; Current carriers; Depletion; Dislocation density; Electric fields; Electrodes; Epitaxial growth; Gallium nitrides; GaN-on-GaN; Heat conductivity; high-energy α-particle detection; Leakage current; low voltage; Nuclear energy; Nuclear power plants; Particle physics; Radiation counters; Radiation detectors; Review; schottky barrier diodes; Schottky diodes; Semiconductors; Silicon carbide; Substrates; thick depletion width detectors; Threading dislocations; Vapor phase epitaxy; Vapor phases; low voltage; GaN-on-GaN; thick depletion width detectors; high-energy α-particle detection; schottky barrier diodes
• DOI: 10.3390/mi11050519
• ISSN: 2072-666X

Among the different semiconductors, GaN provides advantages over Si, SiC and GaAs in radiation hardness, resulting in researchers exploring the development of GaN-based radiation sensors to be used in particle physics, astronomic and nuclear science applications. Several reports have demonstrated the usefulness of GaN as an α-particle detector. Work in developing GaN-based radiation sensors are still evolving and GaN sensors have successfully detected α-particles, neutrons, ultraviolet rays, x-rays, electrons and γ-rays. This review elaborates on the design of a good radiation detector along with the state-of-the-art α-particle detectors using GaN. Successful improvement in the growth of GaN drift layers (DL) with 2 order of magnitude lower in charge carrier density (CCD) (7.6 × 10 /cm ) on low threading dislocation density (3.1 × 10 /cm ) hydride vapor phase epitaxy (HVPE) grown free-standing GaN substrate, which helped ~3 orders of magnitude lower reverse leakage current ( ) with 3-times increase of reverse breakdown voltages. The highest reverse breakdown voltage of -2400 V was also realized from Schottky barrier diodes (SBDs) on a free-standing GaN substrate with 30 μm DL. The formation of thick depletion width (DW) with low CCD resulted in improving high-energy (5.48 MeV) α-particle detection with the charge collection efficiency (CCE) of 62% even at lower bias voltages (-20 V). The detectors also detected 5.48 MeV α-particle with CCE of 100% from SBDs with 30-μm DL at -750 V.