Performance Enhancement of Microwave GaN HEMTs Without an AlN-Exclusion Layer Using an Optimized AlGaN/GaN Interface Growth Process

Bergsten, Johan; Chen, Jr-Tai; Gustafsson, Sebastian; Malmros, Anna; Forsberg, Urban; Thorsell, Mattias; Janzén, Erik; Rorsman, Niklas

doi:10.1109/ted.2015.2501838

Cited by 17 publications

(12 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The details of the device processing for the AlGaN can be found in Ref. 18. A contact resistance of 0.3 X mm was obtained using recessed Ta-based contact.…”

mentioning

confidence: 99%

A GaN–SiC hybrid material for high-frequency and power electronics

Chen

Bergsten

et al. 2018

Applied Physics Letters

Self Cite

View full text Add to dashboard Cite

We demonstrate that 3.5% in-plane lattice mismatch between GaN (0001) epitaxial layers and SiC (0001) substrates can be accommodated without triggering extended defects over large areas using a grain-boundary-free AlN nucleation layer (NL). Defect formation in the initial epitaxial growth phase is thus significantly alleviated, confirmed by various characterization techniques. As a result, a high-quality 0.2-lm thin GaN layer can be grown on the AlN NL and directly serve as a channel layer in power devices, like high electron mobility transistors (HEMTs). The channel electrons exhibit a state-of-the-art mobility of >2000 cm 2 /V-s, in the AlGaN/GaN heterostructures without a conventional thick C-or Fe-doped buffer layer. The highly scaled transistor processed on the heterostructure with a nearly perfect GaN-SiC interface shows excellent DC and microwave performances. A peak RF power density of 5.8 W/mm was obtained at V DSQ ¼ 40 V and a fundamental frequency of 30 GHz. Moreover, an unpassivated 0.2-lm GaN/AlN/SiC stack shows lateral and vertical breakdowns at 1.5 kV. Perfecting the GaN-SiC interface enables a GaN-SiC hybrid material that combines the high-electron-velocity thin GaN with the high-breakdown bulk SiC, which promises further advances in a wide spectrum of high-frequency and power electronics. Published by AIP Publishing.

show abstract

“…The details of the device processing for the AlGaN can be found in Ref. 18. A contact resistance of 0.3 X mm was obtained using recessed Ta-based contact.…”

mentioning

confidence: 99%

A GaN–SiC hybrid material for high-frequency and power electronics

Chen

Bergsten

et al. 2018

Applied Physics Letters

Self Cite

View full text Add to dashboard Cite

show abstract

“…The 2DEG density in a thin-InGaN conducting layer AlGaN/AlN/InGaN/GaN DH significantly increases with increasing In content as may be observed from the experimental Hall data [15][16][17][18][19][20][21] (the formal definition of 'thin' will be provided in the following sections). One intuitively expects that this increment in the 2DEG density is due to a modulation of the polarization charge at the AlGaN/InGaN interface caused by the In content of the InGaN layer.…”

Section: Introductionmentioning

confidence: 80%

Modeling charge density in AlGaN/AlN/InGaN/GaN-based double heterostructures including InGaN layer strain relaxation

Ghosh

2018

J. Phys. Commun.

View full text Add to dashboard Cite

An analytical model is presented to calculate the two-dimensional electron gas (2DEG) density and barrier height of bare surface AlGaN/AlN/InGaN/GaN double heterostructures, which use InGaN as the conducting layer. The basic model is derived from electrostatic analysis of the different material interfaces. The effect of strain relaxation in the InGaN layer is also incorporated here. Further, the impact of a two-dimensional hole gas at the InGaN/GaN interface, formed when the InGaN layer thickness is high, has been considered. The presented results are seen to agree with the available experimental results. Thus, this model can be a useful tool in the design and modeling of InGaN-based III-nitride heterostructures.

show abstract

“…1,2 An additional desirable aspect is the formation of a two-dimensional electron gas (2DEG) at the interface with another III-N semiconductor, typically AlGaN, enabling the fabrication of high electron mobility transistors. [3][4][5][6] In the last decade, such heterostructures, possessing 2DEG, were also in high demand for applications in THz electronics. 7,8 At the epitaxially grown AlGaN/GaN interface, the lattice mismatch and difference in coefficients of thermal expansion (CTE) lead to strain formation.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional electron gas at the AlGaN/GaN interface: Layer thickness dependence

Popok

Caban

Michałowski

et al. 2020

Journal of Applied Physics

View full text Add to dashboard Cite

In the current paper, the structure and properties of AlGaN/GaN interfaces are studied, explaining the role of AlGaN layer thickness on the two-dimensional electron gas (2DEG) formation. It is found that the generation of a continuous electron gas requires AlGaN films with stable stoichiometry, which can be reached only above a certain critical thickness, ≈6-7 nm in our case (20 at. % Al content). Thinner films are significantly affected by oxidation, which causes composition variations and structural imperfections leading to an inhomogeneity of the polarization field and, as a consequence, of the electron density across the interface. Using Kelvin probe force microscopy, this inhomogeneity can be visualized as variations of the surface potential on the sub-micrometer scale. For heterostructures with layer thickness above the critical value, the surface potential maps become homogeneous, reflecting a weakening influence of the oxidation on the interface electronic properties. The 2DEG formation is confirmed by the Hall measurements for these heterostructures.

show abstract

Performance Enhancement of Microwave GaN HEMTs Without an AlN-Exclusion Layer Using an Optimized AlGaN/GaN Interface Growth Process

Cited by 17 publications

References 22 publications

A GaN–SiC hybrid material for high-frequency and power electronics

A GaN–SiC hybrid material for high-frequency and power electronics

Modeling charge density in AlGaN/AlN/InGaN/GaN-based double heterostructures including InGaN layer strain relaxation

Two-dimensional electron gas at the AlGaN/GaN interface: Layer thickness dependence

Contact Info

Product

Resources

About