Differences in electrical responses and recovery of GaN p+n diodes on sapphire and freestanding GaN subjected to high dose 60Co gamma-ray irradiation

Ahn, K.; Ooi, Yu Kee; Mirkhosravi, Farnood; Gallagher, J.; Lintereur, Azaree T.; Feezell, Daniel; Mace, Emily K.; Scarpulla, Michael A.

doi:10.1063/5.0050365

Cited by 6 publications

(3 citation statements)

References 41 publications

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“…Due to the MIS contact behavior, there are charging currents during the actual transition through the flat band state resulting in two minima in the I – V characteristics and thus two flat band states related to the measured voltage at 0.39 and −0.33 V. Such charging currents had already been observed for Schottky contacts in connection with oxide thin films by Splith et al and Ahn et al Due to the hysteresis and the associated stored charge carriers (a 2 → c 1 : positive/holes or c 2 → a 1 : negative/electrons) as well as their different mobilities, the absolute values of the measured voltages differ (a 2 → c 1 : 0.39 V and c 2 → a 1 : −0.33 V).…”

Section: Results and Discussionmentioning

confidence: 66%

Impact of the Tip-to-Semiconductor Contact in the Electrical Characterization of Nanowires

Koch,

Liborius,

Kleinschmidt

et al. 2024

ACS Omega

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Well-defined semiconductor heterostructures are a basic requirement for the development of high-performance optoelectronic devices. In order to achieve the desired properties, a thorough study of the electrical behavior with a suitable spatial resolution is essential. For this, various sophisticated tip-based methods can be employed, such as conductive atomic force microscopy or multitip scanning tunneling microscopy (MT-STM). We demonstrate that in any tip-based measurement method, the tip-to-semiconductor contact is decisive for reliable and precise measurements and in interpreting the properties of the sample. For that, we used our ultrahigh-vacuum-based MT-STM coupled in vacuo to a reactor for the preparation of nanowires (NWs) with metal organic vapor phase epitaxy, and operated our MT-STM as a four-point nanoprober on III−V semiconductor NW heterostructures. We investigated a variety of upright, free-standing NWs with axial as well as coaxial heterostructures on the growth substrates. Our investigation reveals charging currents at the interface between the measuring tip and the semiconductor via native insulating oxide layers, which act as a metal− insulator−semiconductor capacitor with charging and discharging conditions in the operating voltage range. We analyze in detail the observed I−V characteristics and propose a strategy to achieve an optimized tip-to-semiconductor junction, which includes the influence of the native oxide layer on the overall electrical measurements. Our advanced experimental procedure enables a direct relation between the tip-to-NW junction and the electronic properties of as-grown (co)axial NWs providing precise guidance for all future tip-based investigations.

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Section: Results and Discussionmentioning

confidence: 66%

Impact of the Tip-to-Semiconductor Contact in the Electrical Characterization of Nanowires

Koch,

Liborius,

Kleinschmidt

et al. 2024

ACS Omega

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“…Damage processes in semiconductors.-In addition to growthrelated defects, radiation-induced defects in materials are produced through electronic (ionizing and charge transfer) effects and nuclear displacement damage. 166,[176][177][178][179][180][181][182][183][184][185][186][187][188][189][190][191][192][193][194] There may also be damage to insulators used to apply voltage to the gate of a transistor structure. Inelastic linear energy transfer (LET) to the electronic structure (also known as electronic stopping power) from high energy particles, as well as from photons (X-rays and lasers), results in the creation of energetic electrons (i.e., ionization and excitation) that initially dissipate their energy in a cascade of electron-electron energy transfers (superheating) that result in the production of electronhole (e)-(h) pairs (the time scale is <fs); [34][35][36][37][38][39] (2) the transfer of much of this energy via electron-phonon coupling to the atomic structure creating a local thermal spike (the time scale is <300 fs); and (3) the formation of localized electronic excitations that can rupture or change the nature of covalent/ionic bonds, enhance defect and atomic mobilities and increase system energy.…”

Section: Total Dose and Single Event Upsetmentioning

confidence: 99%

Review—Radiation Damage in Wide and Ultra-Wide Bandgap Semiconductors

Pearton

Aitkaliyeva

Xian

et al. 2021

ECS J. Solid State Sci. Technol.

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The wide bandgap semiconductors SiC and GaN are already commercialized as power devices that are used in the automotive, wireless, and industrial power markets, but their adoption into space and avionic applications is hindered by their susceptibility to permanent degradation and catastrophic failure from heavy-ion exposure. Efforts to space-qualify these wide bandgap power devices have revealed that they are susceptible to damage from the high-energy, heavy-ion space radiation environment (galactic cosmic rays) that cannot be shielded. In space-simulated conditions, GaN and SiC transistors have shown failure susceptibility at ∼50% of their nominal rated voltage. Similarly, SiC transistors are susceptible to radiation damage-induced degradation or failure under heavy-ion single-event effects testing conditions, reducing their utility in the space galactic cosmic ray environment. In SiC-based Schottky diodes, catastrophic single-event burnout (SEB) and other single-event effects (SEE) have been observed at ∼40% of the rated operating voltage, as well as an unacceptable degradation in leakage current at ∼20% of the rated operating voltage. The ultra-wide bandgap semiconductors Ga2O3, diamond and BN are also being explored for their higher power and higher operating temperature capabilities in power electronics and for solar-blind UV detectors. Ga2O3 appears to be more resistant to displacement damage than GaN and SiC, as expected from a consideration of their average bond strengths. Diamond, a highly radiation-resistant material, is considered a nearly ideal material for radiation detection, particularly in high-energy physics applications. The response of diamond to radiation exposure depends strongly on the nature of the growth (natural vs chemical vapor deposition), but overall, diamond is radiation hard up to several MGy of photons and electrons, up to 1015 (neutrons and high energetic protons) cm−2 and >1015 pions cm−2. BN is also radiation-hard to high proton and neutron doses, but h-BN undergoes a transition from sp2 to sp3 hybridization as a consequence of the neutron induced damage with formation of c-BN. Much more basic research is needed on the response of both the wide and ultra-wide bandgap semiconductors to radiation, especially single event effects.

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“…In particular, their output power has been observed to decrease under irradiation, reducing the number of photons reaching the detector and accordingly degrading the image quality. In most cases, LEDs can continue to function even after exposure to the TID, although they may exhibit some performance degradation [15].…”

Section: Introductionmentioning

confidence: 99%

Gamma Ray Effects on Multi-Colored Commercial Light-Emitting Diodes at MGy Level

et al. 2022

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Light-emitting diodes (LEDs) are of interest for implementation in radiation environments, such as part of illumination systems of radiation-tolerant cameras able to provide images at high doses (>MGy). It is then mandatory to characterize the radiation effects on all of the LED key properties exploited for such applications. To this aim, the evolution of the optical properties of commercial LEDs after they have been exposed to γ-rays, up to total ionizing dose (TID) levels of 2 MGy(air) at room temperature, is discussed. The devices under test include four LEDs of different colors (red, green, blue and white) in the same package. This allows a direct comparison between the responses of the different structures and technologies, as the proximity between the diodes ensures the uniformity of their irradiation conditions. The radiation effect on the electron–photon conversion mechanisms inside these LEDs is investigated through the evolution of their external quantum efficiency (EQE) vs. current characteristics. The spectral emission pattern of LEDs after irradiation at different dose levels is then characterized to estimate the TID effects on the lens which surrounds the LED package. The presented results show a monotone radiation-induced EQE decrease as a function of the TID, especially in the red LEDs. For the tested red LEDs, the EQE decreased up to 78% after a TID of 1 MGy when they were OFF during irradiation, and up to 8% when they were ON during irradiation. A visual inspection of the devices after irradiation shows a mechanical degradation of the lens shared among the four diodes. However, the emission pattern analysis does not show any significant radiation-induced changes in the optical properties of the lens. Based on these results, it appears possible to design LED-based illumination systems able to survive to MGy dose levels that can be integrated as subsystems of radiation-hardened cameras.

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Differences in electrical responses and recovery of GaN p+n diodes on sapphire and freestanding GaN subjected to high dose 60Co gamma-ray irradiation

Cited by 6 publications

References 41 publications

Impact of the Tip-to-Semiconductor Contact in the Electrical Characterization of Nanowires

Impact of the Tip-to-Semiconductor Contact in the Electrical Characterization of Nanowires

Review—Radiation Damage in Wide and Ultra-Wide Bandgap Semiconductors

Gamma Ray Effects on Multi-Colored Commercial Light-Emitting Diodes at MGy Level

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