Electrostatic Mechanisms Responsible for Device Degradation in Proton Irradiated AlGaN/AlN/GaN HEMTs

Kalavagunta, A.; Touboul, A.; Shen, Li; Schrimpf, R.D.; Reed, Robert A.; Fleetwood, D.M.; Jain, R. K.; Mishra, Umesh K.

doi:10.1109/tns.2008.2001705

Cited by 62 publications

(41 citation statements)

References 23 publications

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“…Many literature papers report that the most probable defect created by proton irradiation is Gallium vacancy, often described as the main responsible of the device degradation in displacement damage, by means of a 2DEG density reduction and mobility degradation [3,9]. First principle simulations correlate the Gallium vacancy point defect to an acceptor-like trap placed 0.80 eV from the valance band [10].…”

Section: Discussionmentioning

confidence: 99%

Proton induced trapping effect on space compatible GaN HEMTs

Stocco

Gerardin

Bisi

et al. 2014

Microelectronics Reliability

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Section: Discussionmentioning

confidence: 99%

Proton induced trapping effect on space compatible GaN HEMTs

Stocco

Gerardin

Bisi

et al. 2014

Microelectronics Reliability

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“…Experimental data from Karmarkar et al, Kalavagunta et al, and Liu et al quantify the amount of mobility reduction for given amounts of proton irradiation as shown in the figure. 5,6,14 Higher proton fluence elicits a larger drop in mobility. Karmarkar at al., Kalavagunta et al, and Patrick et al also quantify the concentration of displacement-related defects (Gallium and Nitrogen vacancies) created by the proton irradiation via TRIM calculations.…”

Section: Resultsmentioning

confidence: 99%

“…Karmarkar at al., Kalavagunta et al, and Patrick et al also quantify the concentration of displacement-related defects (Gallium and Nitrogen vacancies) created by the proton irradiation via TRIM calculations. 5,6,19 We assume that only the acceptor-like Gallium vacancies (V Ga ) are ionized near the two-dimensional electron gas (2DEG) since the Fermi level is above the conduction band edge and thus excludes donor ionization. Thus, V Ga concentrations given by the TRIM simulations are plotted against mobility reductions in Figure 3.…”

Section: Resultsmentioning

confidence: 99%

“…[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 threshold voltage, making a more detailed model requisite.This work explores possible scenarios of HEMT performance degradation due to charged traps in the AlGaN and GaN layers. We first test the hypothesis that mobility reduction due to radiation can be modeled using an ionized impurity scattering model.…”

mentioning

confidence: 99%

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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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“…Detailed evaluation has been performed in order to understand the impact of both proton energy [11] and fluence [9][10][11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%