Effects of Gamma Irradiation on AlGaN-Based High Electron Mobility Transistors

Abstract

The influence of various radiations on the performance and carrier transport properties of AlGaN/GaN HEMTs have been observed at length over the previous few decades. Gamma irradiation has been shown to have little influence on carrier density but has significant effects on device performance. The effects of gamma irradiation have proven non-monotonic in nature, dividing results into low and high doses with an inflection point near 300 Gy. Low doses of gamma irradiation have a tendency to improve device characteristics, while high doses lead to device degradation. The differences in low versus high doses are highlighted by electron beam induced current and dc characterizations. III-Nitride devices have long been an attractive solution to the ever-increasing high power and speed demands of industry. Of note, AlGaN/GaN high electron mobility transistors (HEMTs) have emerged as a contender for these industrial applications investigated due to their high power and speed capabilities.1 Further, AlGaN/GaN HEMT devices do not require additional doping in contrast to AlGaAs/GaAs. Attention to AlGaN/GaN-based devices for potential space and military applications has incited numerous investigations into device radiation hardness.2 Particularly, the effects of high energy radiations on AlGaN/GaN HEMTs have been investigated, as well as p-i-n diodes for solar blind light detectors.Studies of radiation-induced defects in GaN-based devices have attracted significant interest, and much insight exists into the behavior of III-Nitride-based transistors after exposure to energetic ionizing radiation. Investigations of the radiation effects in AlGaN/GaN-based devices employing energetic protons have consistently reported that proton-irradiation results in a decrease in two-dimensional electron gas (2DEG) sheet carrier concentration and a positive threshold voltage shift with increasing proton dose.2-5 Negative threshold voltage shifts and increase in 2DEG sheet concentration have been observed in AlGaN/GaN HEMT structures exposed to 1-MeV neutron irradiation with doses up to 2.5 × 10 15 cm −2 . 6 In contrast to the behavior observed in proton-irradiated HEMTs, negative threshold voltage shifts are also observed in gamma-irradiated devices. 7-9Even at low altitudes, the fluences of high energy protons, electron, and photons may be non-negligible and depend on many factors including the local solar weather. 10 The interaction of highly energetic particles with matter tend to lead to the generation of secondary gamma radiation. Therefore, it becomes critical to interpret the effects of gamma radiation since it is found in low earth orbits and presents with other high energy radiation-matter interactions. Such investigation is very important not only from fundamental point of view, due to obtaining substantial information on the physical properties of semiconductor materials, but it also gives values of the device performance for application in radiation harsh environments.In recent years, the term gamma-ray has been conventionally de...

Effects of gamma irradiation on GaN high-electron-mobility transistors characterized by the voltage-transient method

“…To ensure that the device was in the same initial condition after each detrapping transient measurement, it was recovered completely by shining a 365 nm ultraviolet light of 1 W for 30 s [18,22]. The result that the leakage current of the HEMT decreased after gamma irradiation has been reported in previous studies [4,6,23,24]. Chandan et al suggested that the reduction in leakage current after gamma irradiation corroborates the redistribution of defects [4].…”

“…Therefore, it is crucial to * Author to whom any correspondence should be addressed. study and understand the mechanism of interaction of gamma rays with the material and devices [6][7][8][9].…”

“…Specifically, a gate degradation was identified with a negative gate-source voltage (V GS ) applied to the HEMT at a dose of 3.9 Mrad irradiation [11]. The effects of irradiation on the devices depend on the structures, technologies and experiment conditions [12,13], which may induce the different experiment results [6,14]. However, the change in device performance was normally characterized after irradiation, whereas the improvement or degradation of performance was not monitored during the irradiation process.…”

Nanoscale Stress Localization Effects on the Radiation Susceptibility of GaN High‐Mobility Transistors

“…While lower doses of gamma irradiation are known to enhance performance, [18,19] doses exceeding one are expected to show permanent degradation. This is clearly observed in the measured electrical characteristics in Figure 2.…”

Gamma irradiation impact on GaN quasi-vertical Schottky barrier diodes

“…The gamma irradiation could generate secondary electrons, and these electrons dissipate their kinetic energy in the form of heat and such a process leads to the occupation of trap levels at the interface, thus reducing the trap state density at the Schottky contact interface and reducing the trap assisted tunneling leakage current. Consequently, the overall quality of the diodes would be enhanced by gamma irradiation [35,37].…”