Impact of SF6 plasma treatment on performance of AlGaN/GaN HEMT

Vanko, G.; Lalinský, T.; Hašc̆ı́k, Š.; Rýger, Ivan; Mozolová, Ž.; Škriniarová, J.; Tomáška, M.; Kostič, I.; Vincze, Á.

doi:10.1016/j.vacuum.2009.04.032

Cited by 12 publications

(11 citation statements)

References 8 publications

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“…The same process for gate contact windows increased threshold voltage of drain current. Since the incorporation of F atoms has been reported for SF 6 plasma treatment at AlGaN/GaN surface [9], a similar effect is considered to occur at the exposed AlGaN surface in our process. Figure 4 is a cross-sectional transmission electron microscope (TEM) image at the ohmic contact with 3 nm etching.…”

Section: Resultsmentioning

confidence: 68%

31 GHz power characteristics of GaN HEMTs with slightly etched AlGaN layer at ohmic contact

Hirose

Takada

Matsushita

et al. 2011

Phys. Status Solidi C

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Slight etching of an AlGaN layer at ohmic contact was investigated to reduce contact resistance in AlGaN/GaN HEMTs in Ka‐band operation. In the etching process, etched depth was precisely controlled by ICP‐RIE system with a mixture of BCl3 and Cl2 gases. The relation between ohmic contact resistance and etched depth was examined to determine the optimum depth. It was found that a resistance at an etched depth of 5 nm was reduced to 44% of that in the case of the conventional process. This process was applied to fabrication of GaN HEMTs with a gate length of 0.2 μm, and Ka‐band power characteristics were measured. The linear gain of the device was 11.4 dB, the maximum power‐added efficiency was 45%, and the output power density was 5.1 W/mm, under the conditions of a frequency of 31 GHz, a drain bias of 24 V, and a class‐AB operation. The values are higher than those in the case of the conventional process by 0.5 dB for the linear gain, 2 points for the power‐added efficiency, and 11% for the output power. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Resultsmentioning

confidence: 68%

31 GHz power characteristics of GaN HEMTs with slightly etched AlGaN layer at ohmic contact

Hirose

Takada

Matsushita

et al. 2011

Phys. Status Solidi C

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“…This is consistent with the experimental observations. [8][9][10][11][12][13][14][15] Figure 4a depicts how the F ions density impacts on the ratio of the surface potential to the total potential across the gate/AlGaN/GaN structure. This figure clearly demonstrates that such a ratio decreases with the F ions density increasing.…”

Section: Resultsmentioning

confidence: 99%

“…F plasma treatments have been used to achieve a positive threshold voltage. [8][9][10][11][12][13][14][15] Many groups have reported the results of fluorine implantation with different process conditions but the fluorine concentration in the film was not well controlled, [16][17][18][19][20] and references therein. Fluorine ions have been demonstrated to deplete two-dimensional electron gas directly and a positive shift in the threshold voltage.…”

mentioning

confidence: 99%

“…Fluorine ions have been demonstrated to deplete two-dimensional electron gas directly and a positive shift in the threshold voltage. [8][9][10][11][12][13][14][15] But there lacks a physical model to describe how the immobile negative charges impacts on the device performance. Therefore, developing a physical model of effects the immobile negative charges on device performance is the aim of this paper.…”

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confidence: 99%

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Electrochemical Modeling of the Effects of F Ions in the AlGaN Layer on the Two-Dimensional Electron Density in AlGaN/GaN HEMTs

Mao¹

2019

ECS J. Solid State Sci. Technol.

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Based on electrochemical principles, a new physical model of the F ions in the AlGaN layer on the two-dimensional electron gas of GaN transistors is proposed. The two-dimensional electron gas affected by the F ions in the AlGaN layer calculated by the proposed model can explain those experimental observations reported in the literature. According to the proposed model, the two-dimensional electron gas could physically origins from the electromotive force in the solid electrolyte-the AlGaN layer. The proposed model predicates howthe width of the compact layer, the temperature, the degree of ionization and F ions in the AlGaN layer impacts on the two-dimensional electron gas that still remains to be unraveled. The proposed modelgives a physical understanding ofhow F ions impacts on the performance of GaN-based transistors and supplies a possibility to improve their performance.

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“…[4−8] In recent years, fluorine-based plasma treatment including CF 4 and SF 6 plasmas has been found to be a novel method in realizing positive threshold voltage shift. [9,10] The plasma treatment can effectively incorporate negatively-charged fluorine ions into the AlGaN barrier, resulting in the positive shift of the threshold voltage and the lower gate-leakage currents. In addition, fluorine-based plasma is used to fabricate gate trenches in the dry etch process for the devices with the Si 3 N 4 passivation layer.…”

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confidence: 99%

Impact of CHF₃Plasma Treatment on AlGaN/GaN HEMTs Identified by Low-Temperature Measurement

Yandong¹,

Han²,

Yan³

et al. 2014

Chinese Phys. Lett.

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We investigate the impact of CHF3 plasma treatment on the performance of AlGaN/GaN HEMT (F-HEMT) by a temperature-dependent measurement in the thermal range from 6 K to 295 K. The temperature dependence of the transconductance characteristics in F-HEMT declares that the Coulomb scattering and the optical phonon scattering are effectively enhanced by the fluorine ions in the AlGaN layer. The fluorine ions not only provide immobile negative charges to deplete 2DEG, but also enhance the Schottky barrier height of the metal gate. Thermal activation of the carrier traps induced by CHF3 plasma for F-HEMT contributes to the negative shift of the threshold voltage by −3.4 mV/ ∘ C with the increasing temperature. The reverse gate-leakage current of F-HEMT is decreased by more than two-order magnitude in comparison with that of conventional AlGaN/GaN HEMT (C-HEMT) without fluorine ions.

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Impact of SF6 plasma treatment on performance of AlGaN/GaN HEMT

Cited by 12 publications

References 8 publications

31 GHz power characteristics of GaN HEMTs with slightly etched AlGaN layer at ohmic contact

31 GHz power characteristics of GaN HEMTs with slightly etched AlGaN layer at ohmic contact

Electrochemical Modeling of the Effects of F Ions in the AlGaN Layer on the Two-Dimensional Electron Density in AlGaN/GaN HEMTs

Impact of CHF₃Plasma Treatment on AlGaN/GaN HEMTs Identified by Low-Temperature Measurement

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Impact of SF6 plasma treatment on performance of AlGaN/GaN HEMT

Cited by 12 publications

References 8 publications

31 GHz power characteristics of GaN HEMTs with slightly etched AlGaN layer at ohmic contact

31 GHz power characteristics of GaN HEMTs with slightly etched AlGaN layer at ohmic contact

Electrochemical Modeling of the Effects of F Ions in the AlGaN Layer on the Two-Dimensional Electron Density in AlGaN/GaN HEMTs

Impact of CHF3Plasma Treatment on AlGaN/GaN HEMTs Identified by Low-Temperature Measurement

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Impact of CHF₃Plasma Treatment on AlGaN/GaN HEMTs Identified by Low-Temperature Measurement