With the largest band gap energy of all commercial semiconductors, GaN has found wide application in the making of optoelectronic devices. It has also been used for photodetection such as solar blind imaging as well as ultraviolet and even X-ray detection. Unsurprisingly, the appreciable advantages of GaN over Si, amorphous silicon (a-Si:H), SiC, amorphous SiC (a-SiC), and GaAs, particularly for its radiation hardness, have drawn prompt attention from the physics, astronomy, and nuclear science and engineering communities alike, where semiconductors have traditionally been used for nuclear particle detection. Several investigations have established the usefulness of GaN for alpha detection, suggesting that when properly doped or coated with neutron sensitive materials, GaN could be turned into a neutron detection device. Work in this area is still early in its development, but GaN-based devices have already been shown to detect alpha particles, ultraviolet light, X-rays, electrons, and neutrons. Furthermo...

https://nars.osu.edu/sites/nars.osu.edu/files/uploads/cao-gan_review_for_radiatino_detection.pdf

Review of using gallium nitride for ionizing radiation detection

III-Nitrides are attracting considerable attention as promising materials for a wide variety of applications due to their wide coverage of direct bandgap range, high electron mobility, high thermal stability and many other exceptional properties. The light-emitting diodes based on III-Nitrides revolutionize the solid-state lighting industry. III-Nitrides based solar cells and thermoelectric generators support the sustainable energy progress, and the III-Nitrides are better alternatives for power and radio frequency (RF) electronics compared with silicon. The doped III-Nitrides’ magnetic properties and sensitivity to radiation can contribute to novel spintronic and nuclear detection devices. This paper will review III-nitride material properties and their corresponding applications in LEDs, solar cells, power and radio frequency (RF) electronics, magnetic devices, thermoelectrics and nuclear detection. The typical values of electrical, optical, thermoelectric, magnetic properties are cited, the current state of art investigations are reported, and the future applications are estimated. © The Author(s) 2017. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0101712jss] All rights reserved.

Review—The Current and Emerging Applications of the III-Nitrides

Optical deep level spectroscopy (ODLTS) and microcathodoluminescence (MCL) spectra were measured for a large group of n-GaN samples grown via metalorganic chemical vapor deposition (MOCVD), epitaxial lateral overgrowth (ELOG), or hydride vapor phase epitaxy (HVPE). In the MOCVD and ELOG samples, the ionization energy of dominant hole traps H1 was dependent on the excitation conditions and was ∼0.9 eV for high injection levels providing saturation of the ODLTS peak magnitude. The trap concentration increased with increasing Si donor concentration and correlated with the yellow band intensity in the MCL spectra. For the HVPE samples, the hole trap spectra were radically different from the MOCVD case: four hole traps—H2, H3, H4, and H5—with activation energies of 0.55, 0.65, 0.85, and 1.2 eV, respectively, were detected. In the MCL spectra, a broad green band that peaked near 2.5 eV was observed in addition to the usual yellow luminescence near 2.3 eV. This green band was attributed to the transitions involv...

Comparison of hole traps in n-GaN grown by hydride vapor phase epitaxy, metal organic chemical vapor deposition, and epitaxial lateral overgrowth

The electrical and optical characteristics of an n-type gallium nitride (GaN)-based Schottky barrier ultraviolet (UV) detector, where a platinum (Pt) metal layer forms the anode contact, have been evaluated by means of detailed numerical simulations considering a wide range of incident light intensities. By modeling the GaN physical properties, the detector current density–voltage characteristics and spectral responsivity for different (forward and reverse) bias voltages and temperatures are presented, assuming incident optical power ranging from 0.001 W cm−2 to 1 W cm−2. The effect of defect states in the GaN substrate is also investigated. The results show that, at room temperature and under reverse bias voltage of −300 V, the dark current density is in the limit of 2.18 × 10−19 A cm−2. On illumination by a 0.36-μm UV uniform beam with intensity of 1 W cm−2, the photocurrent significantly increased to 2.33 A cm−2 and the detector spectral responsivity reached a maximum value of 0.2 A W−1 at zero bias voltage. Deep acceptor trap states and high temperature strongly affected the spectral responsivity curve in the considered 0.2 μm to 0.4 μm UV spectral range.

Performance Analysis of a Pt/n-GaN Schottky Barrier UV Detector

Electrical properties and deep electron and hole trap spectra were measured for undoped n-GaN cut from a thick boule grown by hydride vapor phase epitaxy (HVPE). The material is characterized by a very low concentration of residual donors (1013–1014 cm−3) in the first 30 μm near the growth surface. The bulk electrical properties were similar to those of standard high quality undoped bulk HVPE n-GaN, with a net donor concentration of ∼1016 cm−3 and mobility ∼1000 cm2/V s. The strong decrease of electron concentration in the surface region of the high resistivity GaN was caused by the compensation of shallow residual donors by a high density (∼6 × 1015 cm−3) of hole traps with activation energy of 0.2 eV, confined to the compensated region. In addition, other hole traps H5 with activation energy 1.2 eV and concentration 5 × 1015 cm−3 were present. These latter traps had similar concentrations in both the high resistivity and standard conducting HVPE GaN. Radiation detectors prepared on the high resistivity ...

Electrical properties and radiation detector performance of free-standing bulk n-GaN

Ni/GaN Schottky diode radiation detectors were fabricated on 3-μm-thick unintentionally doped n-GaN films grown by molecular beam epitaxy (MBE) and metal organic chemical vapor deposition (MOCVD) and on 12-μm-thick undoped n-GaN layers prepared by epitaxial lateral overgrowth (ELOG). The reverse current of all detector structures was <10−9 A for bias voltages necessary for detector operation, with the level of background donor doping of <1015 cm−3. With this doping level the space charge region of the Schottky diode could be extended to the entire thickness of the films. The charge collection efficiency of the detectors was close to 100% for MOCVD and ELOG detectors for α-particles with range comparable to the thickness of the layer. Electrical properties and deep trap spectra were also studied. The collection efficiency decreased when the concentra-tion of deep electron traps, particularly Ec-0.6 eV traps, increased in MBE grown films.

Alpha particle detection with GaN Schottky diodes

Properties of GaN radiation detectors are analyzed. It is shown that present day epitaxial material is suitable for detection
of α-particles with the charge collection efficiency close to 100%. Such detectors can operate at temperatures of at least
60°C and withstand irradiation with reactor neutrons fluences higher than 1015 cm -2 . They keep the collection efficiency
at 30% even after irradiation with 2×1016 cm -2 neutron fluence. Registration of thermal neutrons with GaN detectors can
also be achieved by using 10 B converter and the efficiency of registration is determined by the 10 B conversion efficiency
from neutrons to low energy a-particles.

V. M. Zalyetin

Papers

Alpha particle detection with GaN Schottky diodes

GaN as a detector of α-particles and neutrons