Electrical, spectral, and chemical properties of 1.8 MeV proton irradiated AlGaN/GaN HEMT structures as a function of proton fluence

White, B. D.; Bataiev, M.; Goss, S. H.; Hu, Xudong; Karmarkar, Aditya P.; Fleetwood, D.M.; Schrimpf, R.D.; Schaff, William J.; Brillson, L. J.

doi:10.1109/tns.2003.821827

Cited by 85 publications

(65 citation statements)

References 21 publications

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“…Quasi in situ measurements enabled us to monitor the capacitance during the bombardment. In accordance with previous experiments [5,10] was observed. Photo-capacitance transient measurements allowed for the measurement of the degree of acceptor compensation in the sample.…”

Section: Discussionsupporting

confidence: 92%

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Introduction and annealing of primary defects in proton‐bombarded n‐GaN

Schmidt

Meyer

Rensburg

et al. 2013

Physica Status Solidi (b)

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We report on in situ space charge spectroscopy measurements on low‐temperature 1.6thinmathspaceMeV proton‐bombarded n‐type gallium nitride thin film samples. The scope of this study was to investigate the introduction and annealing dynamics of radiation‐induced lattice damage. Using optical excitation allowed for the detection of electronic defect states in the entire GaN bandgap and to detect unstable primary defects that would have been invisible in thermal space charge spectroscopic measurements. The introduction of compensating acceptor‐like primary defects by the bombardment was observed and manifested as a decrease in the sample capacitance. After the bombardment the concentrations of deep‐levels and acceptor states were monitored by deep‐level transient spectroscopy and photo‐capacitance measurements while the temperature was increased. It was found that annealing and reactions of primary bombardment‐induced defects occurs even below room‐temperature which might account for the radiation‐hardness of GaN.

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Section: Discussionsupporting

confidence: 92%

“…The radiation hardness of GaN has previously been investigated in GaN thin films [2][3][4][5][6][7], single crystals [8], nanowires [9], and devices [10,11]. An overview on radiation effects in GaN can be found in Ref.…”

Section: Introductionmentioning

confidence: 99%

Introduction and annealing of primary defects in proton‐bombarded n‐GaN

Schmidt

Meyer

Rensburg

et al. 2013

Physica Status Solidi (b)

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“…The effect was explained by the formation of a negatively charged defect interfacial layer near the Ni/GaN boundary. Similar increase by about 0.1 eV in the Ni/ GaN Schottky barrier height was reported for the Schottky gates of AlGaN/GaN HEMTs irradiated with 1.8 MeV protons for protons doses in excess of 10 14 cm -2 [67]. We observed similar slight Schottky barrier height increase for Au and Ni n-GaN fi lms after irradiation with fast reactor neutrons and 10 MeV electrons.…”

Section: Radiation Effects In Gan Schottky Diodes In Algan/gan and Gsupporting

confidence: 87%

Radiation Damage in GaN‐Based Materials and Devices

Patrick

Law

Pearton

et al. 2014

Advanced Energy Materials

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A review of electron, proton and neutron damage in GaN and AlGaN materials and devices such as high electron mobility transistors and lightemitting diodes is presented. A comparison of theoretical and experimental threshold displacement energies is given, along with a summary of energy levels introduced by different forms of radiation, carrier removal rates and role of existing defects. Many studies have shown that GaN is several orders of magnitude more resistant to radiation damage than GaAs, i.e., it can withstand radiation doses at least two orders of magnitude higher than those degrading GaAs of similar doping level. In terms of heterostructures, the initial data suggests that the radiation hardness decreases in the order AlN/GaN >AlGaN/GaN > InAlN/GaN, consistent with the average bond strengths in the Al-based materials. Many issues still have to be addressed. Among them are the strong asymmetry in carrier removal rates in n-and p-type GaN and interaction of radiation defects with Mg acceptors, and the poor understanding of the interaction of radiation defects in doped nitrides with the dislocations always present.

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“…The ionization function for a donor trap is shown in Equation 4. [4] where N D is the donor trap concentration, N + D is the ionized donors, and E F and E T are the electron quasi-Fermi level and trap level respectively. This equation leads to a steep function around the trap level that plateaus on either side.…”

Section: Methodsmentioning

confidence: 99%

Simulation of Radiation Effects in AlGaN/GaN HEMTs

Patrick

Choudhury

Ren

et al. 2015

ECS J. Solid State Sci. Technol.

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AlGaN/GaN high electron mobility transistors (HEMTs) are desirable for space applications because of their relative radiation hardness. Predictive modeling of these devices is therefore desired; however, physics-based models accounting for radiation-induced degradation are incomplete. In this work, we show that a partially ionized impurity scattering mobility model can explain the observed reduction in mobility. Electrostatic changes can be explained by confinement of negative charge near the 2DEG in the GaN buffer layer. Simulation results from FLOODS (a TCAD simulator) demonstrate that partial ionization of donor traps is responsible for this phenomenon. Compensation of the acceptor traps by the ionized donors in the GaN confine the acceptor traps (negative space charge) to a thin layer near the AlGan/GaN interface. The simulation results show that near equal concentrations of acceptor traps and donor traps of 1 × 10 17 cm −3 can account for the performance degradation of HEMTs given 5 MeV proton radiation at a fluence of 2 × 10 14 cm −2 . Our results imply that device performance can be accurately simulated by simultaneously accounting for mobility and electrostatic degradation in TCAD solvers using the presented approach. Over the last ten years, there has been a significant amount of research evaluating the effects of radiation on the performance of GaNbased high electron mobility transistors (HEMTs). In general, protonbased radiation damage to AlGaN/GaN HEMTs results in mobility degradation and an increase in the threshold voltage, both of which lead to reductions in peak transconductance and drain current. 1-17The change in mobility has the potential to be greater in magnitude than changes observed in the other parameters. For example Lu et al. measured 40% reduction in mobility and only a 0.1V shift (3% change) in threshold voltage and 13% reduction in drain saturation current for a specific case of proton radiation.14 Additionally, Gaudreau measured a decrease in carrier concentration by a factor of two and a decrease in mobility by a factor of a thousand in response to proton radiation. 1More insight is needed with respect to how radiation defects affect both electron mobility and device electrostatics. Confirmed physics-based models will allow prediction of device performance that depends on the coupled interplay of both parameters.Changes in device performance are primarily attributed to charged point defects, including vacancies and interstitials created by the radiation damage.18 While both donor-and acceptor-like traps are expected to be created during irradiation, it has been shown that a majority of acceptor-like traps are necessary to explain the positive shifts in threshold voltage. [6][7][8]19 Coulombic interaction with charged, radiationinduced defect states has been suggested as the physical reason for mobility reduction. 3,5,6,20 However preliminary calculations show that the concentration of ionized traps responsible for mobility reduction is incompatible with the reduced change in thresh...

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Electrical, spectral, and chemical properties of 1.8 MeV proton irradiated AlGaN/GaN HEMT structures as a function of proton fluence

Cited by 85 publications

References 21 publications

Introduction and annealing of primary defects in proton‐bombarded n‐GaN

Introduction and annealing of primary defects in proton‐bombarded n‐GaN

Radiation Damage in GaN‐Based Materials and Devices

Simulation of Radiation Effects in AlGaN/GaN HEMTs

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