Electron mobility in graded AlGaN alloys

Rajan, Siddharth; DenBaars, Steven P.; Mishra, Umesh K.; Xing, Huili Grace; Jena, Debdeep

doi:10.1063/1.2165190

Cited by 43 publications

(26 citation statements)

References 10 publications

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“…In addition, the multiphonon-emission capture process, related to a lower E b , can be enhanced at interfaces with the higher degree of mismatch due to inducing strains resulting in larger r. This explanation can be supported by the fact that the examined structures contained thin barriers layers (Al x Ga 1Àx N and In x Al 1Àx N) of about 25 nm in thickness, and thus fully strained for x up to about 0.4, according to the literatures. [36][37][38][39] On the contrary, from the theoretical calculation and capacitance/conductivity measurements 40 it is known that the bulk mobility (l) in AlGaN decreases with x due to alloy-scattering limited. Therefore, because L $ l we expect that L also deceases with x and thus r increases with x, according to Eq.…”

Section: Discussionmentioning

confidence: 99%

Characterization of capture cross sections of interface states in dielectric/III-nitride heterojunction structures

Matys

Stoklas

Kuzmı́k

et al. 2016

Journal of Applied Physics

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Articles you may be interested inWe performed, for the first time, quantitative characterization of electron capture cross sections r of the interface states at dielectric/III-N heterojunction interfaces. We developed a new method, which is based on the photo-assisted capacitance-voltage measurements using photon energies below the semiconductor band gap. The analysis was carried out for AlGaN/GaN metal-insulatorsemiconductor heterojunction (MISH) structures with Al 2 O 3 , SiO 2 , or SiN films as insulator deposited on the AlGaN layers with Al content (x) varying over a wide range of values. Additionally, we also investigated an Al 2 O 3 /InAlN/GaN MISH structure. Prior to insulator deposition, the AlGaN and InAlN surfaces were subjected to different treatments. We found that r for all these structures lies in the range between 5 Â 10 À19 and 10 À16 cm 2 . Furthermore, we revealed that r for dielectric/ Al x Ga 1Àx N interfaces increases with increasing x. We showed that both the multiphonon-emission and cascade processes can explain the obtained results. Published by AIP Publishing.

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Section: Discussionmentioning

confidence: 99%

Characterization of capture cross sections of interface states in dielectric/III-nitride heterojunction structures

Matys

Stoklas

Kuzmı́k

et al. 2016

Journal of Applied Physics

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“…Such parallel 2D hole sheets suffer from low conductivity along the c vertical axis.because of large potential barriers that require the hole to transport through tunneling or thermionic emission processes caused by strong polarization fields and valence band discontinuity 30 31 32 33 , although they have high in-plane conductivity. Furthermore, hole scatterings become increasingly significant as Al content increases, which aggravates low vertical hole mobility 34 35 36 . In this case, developing an alternative strategy for efficient p -type doping and hole injection in Al-rich AlGaN devices is highly desirable.…”

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confidence: 99%

Improved p-type conductivity in Al-rich AlGaN using multidimensional Mg-doped superlattices

Zheng

Lin

Liu

et al. 2016

Sci Rep

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A novel multidimensional Mg-doped superlattice (SL) is proposed to enhance vertical hole conductivity in conventional Mg-doped AlGaN SL which generally suffers from large potential barrier for holes. Electronic structure calculations within the first-principle theoretical framework indicate that the densities of states (DOS) of the valence band nearby the Fermi level are more delocalized along the c-axis than that in conventional SL, and the potential barrier significantly decreases. Hole concentration is greatly enhanced in the barrier of multidimensional SL. Detailed comparisons of partial charges and decomposed DOS reveal that the improvement of vertical conductance may be ascribed to the stronger pz hybridization between Mg and N. Based on the theoretical analysis, highly conductive p-type multidimensional Al0.63Ga0.37N/Al0.51Ga0.49N SLs are grown with identified steps via metalorganic vapor-phase epitaxy. The hole concentration reaches up to 3.5 × 1018 cm−3, while the corresponding resistivity reduces to 0.7 Ω cm at room temperature, which is tens times improvement in conductivity compared with that of conventional SLs. High hole concentration can be maintained even at 100 K. High p-type conductivity in Al-rich structural material is an important step for the future design of superior AlGaN-based deep ultraviolet devices.

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“…Moreover, the observation of the lowest mobility (723 cm 2 V À1 s À1 ) in sample-D can also be explained by degraded crystal quality. In addition, a low mobility three-dimensional channel originating from the graded AlGaN layer could be formed in parallel with the main 2-D channel [35]. Small differences in Indium compositions of the AlInN barrier layers (revealed by XRD analyses) might have effect on the mobility of the samples.…”

Section: Resultsmentioning

confidence: 99%

Investigation of AlInN HEMT structures with different AlGaN buffer layers grown on sapphire substrates by MOCVD

Kelekçi

Tasli

Çetin

et al. 2012

Current Applied Physics

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Cataloged from PDF version of article.We investigate the structural and electrical properties of AlxIn1-xN/AlN/GaN heterostructures with AlGaN buffers grown by MOCVD, which can be used as an alternative to AlInN HEMT structures with GaN buffer. The effects of the GaN channel thickness and the addition of a content graded AlGaN layer to the structural and electrical characteristics were studied through variable temperature Hall effect measurements, high resolution XRD, and AFM measurements. Enhancement in electron mobility was observed in two of the suggested AlxIn1-xN/AlN/GaN/Al0.04Ga0.96N heterostructures when compared to the standard AlxIn1-xN/AlN/GaN heterostructure. This improvement was attributed to better electron confinement in the channel due to electric field arising from piezoelectric polarization charge at the Al0.04Ga0.96N/GaN heterointerface and by the conduction band discontinuity formed at the same interface. If the growth conditions and design parameters of the AlxIn1-xN HEMT structures with AlGaN buffers can be modified further, the electron spillover from the GaN channel can be significantly limited and even higher electron mobilities, which result in lower two-dimensional sheet resistances, would be possible. (C) 2012 Elsevier B.V. All rights reserved

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Electron mobility in graded AlGaN alloys

Cited by 43 publications

References 10 publications

Characterization of capture cross sections of interface states in dielectric/III-nitride heterojunction structures

Characterization of capture cross sections of interface states in dielectric/III-nitride heterojunction structures

Improved p-type conductivity in Al-rich AlGaN using multidimensional Mg-doped superlattices

Investigation of AlInN HEMT structures with different AlGaN buffer layers grown on sapphire substrates by MOCVD

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