2MeV ion irradiation effects on AlGaN/GaN HFET devices

Sonia, G.; Richter, E.; Brunner, F.; Denker, A.; Lossy, R.; Mai, M.; Lenk, F.; Bundesmann, J.; Pensl, Gerhard; Schmidt, J.; Zeimer, U.; Wang, L.; Baskar, K.; Weyers, M.; Würfl, Joachim; Tränkle, G.

doi:10.1016/j.sse.2008.02.005

Cited by 26 publications

(14 citation statements)

References 12 publications

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“…What is worse, the gate-voltageswing (GVS) also degrades from 1 V to 0.6 V after proton irradiation, which might lead to a large intermodulation distortion, a large phase noise, and a small dynamic range for HEMTs [12]. The drastic degradation of HEMT is due to the defect centers introduced in the AlGaN layer that lead to a lower carrier density in the 2DEG and lower carrier mobility [10]. For the NbAlO MIS-HEMT, as shown in Figure 2, at the same fluence, I DS only decreases from 904 mA/mm to 842 mA/mm while g m decreases from 132 mS/mm to 125 mS/mm.…”

Section: Resultsmentioning

confidence: 99%

“…Figure 1 shows the capacitance-voltage (C-V) characteristics and the heterointerface-carriers distribution of NbAlO MIS-HEMTs before and after 3 MeV proton-irradiation. In Figure 1(a), after proton irradiation, there is a forward flat-band voltage shift of about 0.94 V. The main reason for this shift is that the decreased carrier concentration, resulting from radiation-induced defect centers sites in AlGaN layer, can be exhausted under a low electric field [10]. From the C-V curve, we can get the carrier concentration (N CV ) versus the depletion region depth of the MIS-HEMTs [11].…”

Section: Methodsmentioning

confidence: 99%

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The effects of proton irradiation on the electrical properties of NbAlO/AlGaN/GaN MIS-HEMT

Feng

Zhang

et al. 2011

Sci. China Phys. Mech. Astron.

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AlGaN/GaN metal-insulator-semiconductor high electron-mobility transistors (MIS-HEMTs) with atomic layer deposited (ALD) NbAlO gate dielectric were investigated using 3 MeV proton irradiation at a fluence of 10 15 p/cm 2 . It was found that the proton irradiation damage caused degradation in DC performance and a flatband voltage shift in the capacitance-voltage curve. Gate-drain conductance measurements indicated that new traps were introduced in GaN from the irradiation, and the trap densities increased from 1.18×10 12 cm 2 eV 1 to 1.82×10 12 cm 2 eV 1 in MIS-HEMTs after irradiation. However, these increases in trap densities caused by irradiation in MIS-HEMT are less than those in HEMT, which can be attributed to the protection of the AlGaN surface by the NbAlO dielectric layer. AlGaN/GaN, MIS-HEMT, proton irradiation, trap PACS number(s): 85.30.Tv, 73.40.Qv, 77.55.+f, 61.82.Fk Citation:AlGaN/GaN high electron-mobility transistors (HEMTs) have recently emerged as attractive transistors suitable for high-power and high-frequency applications [1]. However, larger gate leakage currents in HEMTs due to surface defects and the finite barrier height of AlGaN limit the performance and reliability of devices, especially the breakdown voltage and power handling capabilities [2]. Previously, several groups have attempted to solve this problem by applying the metal-insulator-semiconductor (MIS) structure. For example, S i O 2 [3], Al 2 O 3 [4], and HfO 2 [5] have all been widely used for gate dielectric layers. The high-k dielectric layer can be thickened without reducing the transconductance of HEMTs. In this paper, we choose atomic layer deposition (ALD) Nb0.1Al0.9O as the gate insulator layer, because it has a larger bandgap (6.7) than HfO 2 and a higher dielectric constant (15) than Al 2 O 3 . The NbAlO MISHEMTs have been fabricated successfully and the gate leakage current decreased about three orders of magnitude less than HEMT [6]. In addition, GaN-based devices are radiation harder than GaAs devices, and hence are known for several unique applications, such as satellite-based communication systems and nuclear industry applications [7], in which devices would be set in place where they are exposed to a great deal of particle radiation. Therefore, GaN-based devices are expected to have higher resistance against radiation than conventional devices. Previous studies observed significant degradation in the performances of AlGaN/GaN HEMTs after a fluence of 10 14 10 15 p/cm 2 1.8 MeV protons [8]. The degradation is identified by a decrease in the maximum transconductance, an increase in the threshold voltage, and a decrease in the drain saturation

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

The effects of proton irradiation on the electrical properties of NbAlO/AlGaN/GaN MIS-HEMT

Feng

Zhang

et al. 2011

Sci. China Phys. Mech. Astron.

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“…The initial work on effect of proton irradiation on GaN-based heterostructures involved light-emitting diodes, 1 while subsequent work has focused on AlGaN/GaN HEMTs. [2][3][4][5][6][7][8][9][10] For a proton fluence of 10 14 /cm 2 at 1.8 MeV energy, reductions of saturation drain current (I DSS ) and transconductance (g m ) in HEMTs from 260 to 100 mA/mm and from 80 to 26 mS/mm, respectively, were reported. 2 Similar proton energy studies at different energies were performed by Hu et al 3 and White et al, 5 which found little degradation and good radiation tolerance of the device channel at fluences up to 10 14 /cm 2 .…”

Section: Introductionmentioning

confidence: 99%

Dependence on proton energy of degradation of AlGaN/GaN high electron mobility transistors

Liu

et al. 2013

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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The effects of proton irradiation energy on dc, small signal, and large signal rf characteristics of AlGaN/GaN high electron mobility transistors (HEMTs) were investigated. AlGaN/GaN HEMTs were irradiated with protons at fixed fluence of 5 × 1015/cm2 and energies of 5, 10, and 15 MeV. Both dc and rf characteristics revealed more degradation at lower irradiation energy, with reductions of maximum transconductance of 11%, 22%, and 38%, and decreases in drain saturation current of 10%, 24%, and 46% for HEMTs exposed to 15, 10, and 5 MeV protons, respectively. The increase in device degradation with decreasing proton energy is due to the increase in linear energy transfer and corresponding increase in nonionizing energy loss with decreasing proton energy in the active region of the HEMTs. After irradiation, both subthreshold drain leakage current and reverse gate current decreased more than 1 order of magnitude for all samples. The carrier removal rate was in the range 121–336 cm−1 over the range of proton energies employed in this study.

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“…In 2004, Hu et al 1 reported the energy dependence of proton-induced degradation and recovery of AlGaN/GaN HFETs. In 2008, Sonia et al 2 studied the effect of 2 MeV proton-irradiation on HFETs and found that irradiation with protons up to fluences of 10 13 cm −2 did not degrade the operation of the devices. In 2007, low-energy ͑0.45 MeV͒ electron-irradiation ͑EI͒ effects on HFETs were investigated at low temperature ͑ϳ85 K͒ by McClory et al 3 In that study, increases in the drain and gate currents and a shift in the threshold voltage found at low temperatures were discussed in terms of positive charge buildup and the trap formation in the AlGaN layer ͑or near the interface͒.…”

Section: Introductionmentioning

confidence: 99%

Effects of electron-irradiation on electrical properties of AlGaN/GaN Schottky barrier diodes

Fang

Farlow

Claflin

et al. 2009

Journal of Applied Physics

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Effects of 1 MeV electron-irradiation at room temperature on the electrical properties of AlGaN/ GaN heterostructures, including leakage currents, threshold voltages, and electron traps, have been investigated using Schottky barrier diodes ͑SBDs͒ fabricated on the AlGaN. The SBDs, before and after the irradiation with a dose of 5 ϫ 10 15 cm −2 , were characterized by temperature dependent current-voltage and capacitance-voltage measurements and deep level transient spectroscopy. It is found that the irradiation causes ͑i͒ significant increase in leakage currents, dominated by tunneling conduction, at both reverse and low-forward biases; ͑ii͒ a clear negative shift in threshold voltage in the pinch-off region; and ͑iii͒ creation of traps A e ͑ϳ1.1 eV͒ or A 2 ͑1.2 eV͒ and E e ͑0.09 eV͒ in the GaN buffer and AlGaN regions. The irradiation-induced traps can be used to account for the increase in leakage currents and shift in threshold voltage. However, as compared to traps A 2 ͑1.2 eV͒ and E͑0.13 eV͒ induced in thick GaN layers by electron-irradiation, the irradiation-induced traps in the AlGaN/GaN heterostructures show some changes in activation energy and electron capture behavior.

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2MeV ion irradiation effects on AlGaN/GaN HFET devices

Cited by 26 publications

References 12 publications

The effects of proton irradiation on the electrical properties of NbAlO/AlGaN/GaN MIS-HEMT

The effects of proton irradiation on the electrical properties of NbAlO/AlGaN/GaN MIS-HEMT

Dependence on proton energy of degradation of AlGaN/GaN high electron mobility transistors

Effects of electron-irradiation on electrical properties of AlGaN/GaN Schottky barrier diodes

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