Room-temperature mobility above 2200 cm2/V·s of two-dimensional electron gas in a sharp-interface AlGaN/GaN heterostructure

Chen, Jr-Tai; Persson, Ingemar; Nilsson, Daniel; Hsu, Chih-Wei; Pališaitis, Justinas; Forsberg, Urban; Persson, Per O. Å.; Janzén, Erik

doi:10.1063/1.4922877

Cited by 49 publications

(37 citation statements)

References 20 publications

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“…The OHE signal from the 2DEG is enhanced by the substrate/air-gap cavity and can be observed in the off diagonal block elements of the Mueller matrix The 2DEG density and mobility parameters are consistent with the respective values typically reported for AlGaN/GaN HEMTs [61,62]. The 2DEG effective mass parameter is somewhat higher than the bulk GaN electron mass of 0.232m 0 [63], which is in agreement with previous reports [55,59,64].…”

Section: Terahertz Optical Hall Effect (Thz-ohe)supporting

confidence: 80%

“…We employ a neodymium permanent magnet with a surface field of B = 0.55 T and a fixed cavity of d = 100µm between the sample and the surface of the permanent magnet. The HEMT structure consists of an Al 0.75 Ga 0.25 N barrier layer on 2-µm-thick GaN layer on a 4H-SiC substrate employing an AlN nucleation layer [61]. Figure 8 shows experimental (symbols) OHE data together with best model calculations (lines) for two opposing magnetic field directions perpendicular to the sample surface, together with the respective difference.…”

Section: Terahertz Optical Hall Effect (Thz-ohe)mentioning

confidence: 99%

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Advanced Terahertz Frequency-Domain Ellipsometry Instrumentation for In Situ and Ex Situ Applications

Kühne

Armakavicius

Stanishev

et al. 2018

IEEE Trans. THz Sci. Technol.

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Abstract-We present a terahertz (THz) frequency-domain spectroscopic (FDS) ellipsometer design which suppresses formation of standing waves by use of stealth technology approaches. The strategy to suppress standing waves consists of three elements geometry, coating and modulation. The instrument is based on the rotating analyzer ellipsometer principle and can incorporate various sample compartments, such as a superconducting magnet, in-situ gas cells or resonant sample cavities, for example. A backward wave oscillator and three detectors are employed, which permit operation in the spectral range of 0.1-1 THz (3.3-33 cm −1 or 0.4-4 meV). The THz frequency-domain ellipsometer allows for standard and generalized ellipsometry at variable angles of incidence in both reflection and transmission configurations. The methods used to suppress standing waves and strategies for an accurate frequency calibration are presented. Experimental results from dielectric constant determination in anisotropic materials, and free charge carrier determination in optical Hall effect, resonant-cavity enhanced optical Hall effect and in-situ optical Hall effect experiments are discussed. Examples include silicon and sapphire optical constants, free charge carrier properties of two dimensional electron gas in group-III nitride high electron mobility transistor structure, and ambient effects on free electron mobility and density in epitaxial graphene.

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Section: Terahertz Optical Hall Effect (Thz-ohe)supporting

confidence: 80%

Section: Terahertz Optical Hall Effect (Thz-ohe)mentioning

confidence: 99%

Advanced Terahertz Frequency-Domain Ellipsometry Instrumentation for In Situ and Ex Situ Applications

Kühne

Armakavicius

Stanishev

et al. 2018

IEEE Trans. THz Sci. Technol.

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“…Gate structuring is realized by selective dry-etching of the p-GaN epitaxial layer in an early phase of the complete device process [20,22]. Selective overgrowth of the p-GaN region has also been reported [2,8]. The process sequence has to be selected properly as it depends on the annealing hierarchies of the different metallizations used for contacting the p-GaN gate and the source/drain ohmic contacts.…”

Section: Normally-off Transistors With P-gan Gate: Technology and Permentioning

confidence: 99%

“…This means that a 1 µm-thick GaN layer can theoretically withstand 330 V, whereas a Si layer with the same thickness shows breakdown around 30 V. Thanks to the high breakdown field of GaN, lateral transistors with breakdown voltages higher than 1900 V have already been demonstrated [1]. In lateral GaN HEMTs, a two-dimensional electron gas (2DEG) is formed at the interface between GaN and AlGaN; the high mobility of the 2DEG (in excess of 2000 cm 2 /Vs [2]) results in current densities around 1 A/mm, and in a very low on resistance (25 mΩ for a 650 V/60 A device [3]). This implies a significant reduction in the switching losses, with positive impact on the efficiency of GaN-based power converters.…”

Section: Introductionmentioning

confidence: 99%

“…In principle, when the HEMT is used as a switch, current and voltage should never be high simultaneously. However, in a hard switching event (labeled as (2) in Figure 1), during the turnon of the transistor the drain current can start to increase before the drain-source voltage of the HEMT drops. During the turn-on transient, the drain current can exceed the inductor current IL, due to the discharge of the drain capacitance through the channel (as explained in [5]), and then become (approximately) equal to the inductor current IL.…”

Section: Introductionmentioning

confidence: 99%

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Technology and Reliability of Normally-Off GaN HEMTs with p-Type Gate

et al. 2017

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Abstract:GaN-based transistors with p-GaN gate are commonly accepted as promising devices for application in power converters, thanks to the positive and stable threshold voltage, the low on-resistance and the high breakdown field. This paper reviews the most recent results on the technology and reliability of these devices by presenting original data. The first part of the paper describes the technological issues related to the development of a p-GaN gate, and the most promising solutions for minimizing the gate leakage current. In the second part of the paper, we describe the most relevant mechanisms that limit the dynamic performance and the reliability of GaN-based normally-off transistors. More specifically, we discuss the following aspects: (i) the trapping effects specific for the p-GaN gate; (ii) the time-dependent breakdown of the p-GaN gate during positive gate stress and the related physics of failure; (iii) the stability of the electrical parameters during operation at high drain voltages. The results presented within this paper provide information on the current status of the performance and reliability of GaN-based E-mode transistors, and on the related technological issues.

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The Effect of AlN Buffer Layer on AlGaN/GaN/AlN Double‐Heterostructure High‐Electron‐Mobility Transistor

Choi

Jung

Lee

et al. 2019

Physica Status Solidi (a)

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Herein, the effect of crystal quality of AlN buffer layer on AlGaN/GaN/AlN double‐heterostructure high‐electron‐mobility transistor (DH‐HEMT) is investigated. The material quality of the GaN channel and the AlGaN barriers, such as the dislocation density and the interface roughness, deteriorates, and the 2D electron gas (2DEG) mobility decreases as the threading dislocation density (TDD) of the AlN buffer increases. It is also revealed that the thickness and the Al mole fraction of the AlGaN barrier are affected by the strain variation of the GaN channel depending on the TDD of the AlN buffer. The variation of the compressive strain of the GaN channel is responsible for the 2DEG density change by affecting the barrier condition and the piezoelectric polarization charge. Low‐temperature Hall effect measurement reveals that the interface roughness scattering is a dominant factor for the mobility of the DH‐HEMT, which is ≈2–6 × 103 cm2 (V s)−1.

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Room-temperature mobility above 2200 cm2/V·s of two-dimensional electron gas in a sharp-interface AlGaN/GaN heterostructure

Abstract: , Room-Temperature mobility above 2200 cm2/V.s of two-dimensional electron gas in a sharp-interface AlGaN/GaN heterostructure, 2015, Applied Physics Letters, (106), 25. http://dx

Cited by 49 publications

References 20 publications

Advanced Terahertz Frequency-Domain Ellipsometry Instrumentation for In Situ and Ex Situ Applications

Advanced Terahertz Frequency-Domain Ellipsometry Instrumentation for In Situ and Ex Situ Applications

Technology and Reliability of Normally-Off GaN HEMTs with p-Type Gate

The Effect of AlN Buffer Layer on AlGaN/GaN/AlN Double‐Heterostructure High‐Electron‐Mobility Transistor

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