Polarization-induced valence-band alignments at cation- and anion-polar InN∕GaN heterojunctions

Wu, Chi Jung; Lee, Hong Mao; Kuo, Cheng-Tai; Gwo, Shangjr; Hsu, Chia Chi

doi:10.1063/1.2764448

Cited by 37 publications

(28 citation statements)

References 19 publications

(13 reference statements)

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“…These experimental results are in contrast to measurements of polarization effects at interfaces between two polar crystalline materials such as InN and GaN. 50 In this case as in other polar-polar crystalline interfaces, the interface dipole due to the polarization charge is manifested as an evident change in the VBO for opposite polar configurations. However, the relatively small band bending on Ga-and N-face GaN indicated that the polarization charge is largely screened by a high concentration of interface states.…”

Section: Interface Dipole and Polarizationcontrasting

confidence: 53%

Surface band bending and band alignment of plasma enhanced atomic layer deposited dielectrics on Ga- and N-face gallium nitride

Yang

Eller

Nemanich

2014

Journal of Applied Physics

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The effects of surface pretreatment, dielectric growth, and post deposition annealing on interface electronic structure and polarization charge compensation of Ga-and N-face bulk GaN were investigated. The cleaning process consisted of an ex-situ wet chemical NH 4 OH treatment and an in-situ elevated temperature NH 3 plasma process to remove carbon contamination, reduce oxygen coverage, and potentially passivate N-vacancy related defects. After the cleaning process, carbon contamination decreased below the x-ray photoemission spectroscopy detection limit, and the oxygen coverage stabilized at $1 monolayer on both Ga-and N-face GaN. In addition, Ga-and N-face GaN had an upward band bending of 0.8 6 0.1 eV and 0.6 6 0.1 eV, respectively, which suggested the net charge of the surface states and polarization bound charge was similar on Ga-and N-face GaN. Furthermore, three dielectrics (HfO 2 , Al 2 O 3 , and SiO 2 ) were prepared by plasma-enhanced atomic layer deposition on Ga-or N-face GaN and annealed in N 2 ambient to investigate the effect of the polarization charge on the interface electronic structure and band offsets. The respective valence band offsets of HfO 2 , Al 2 O 3 , and SiO 2 with respect to Ga-and N-face GaN were 1.4 6 0.1, 2.0 6 0.1, and 3.2 6 0.1 eV, regardless of dielectric thickness. The corresponding conduction band offsets were 1.0 6 0.1, 1.3 6 0.1, and 2.3 6 0.1 eV, respectively. Experimental band offset results were consistent with theoretical calculations based on the charge neutrality level model. The trend of band offsets for dielectric/GaN interfaces was related to the band gap and/or the electronic part of the dielectric constant. The effect of polarization charge on band offset was apparently screened by the dielectric-GaN interface states. V C 2014 AIP Publishing LLC.

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Section: Interface Dipole and Polarizationcontrasting

confidence: 53%

Surface band bending and band alignment of plasma enhanced atomic layer deposited dielectrics on Ga- and N-face gallium nitride

Yang

Eller

Nemanich

2014

Journal of Applied Physics

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“…The VB offset between GaN and InN has been measured in a number of studies. 4,[21][22][23][24][25][26][27][28] The most recent experimental study reported an offset of 0.58 ± 0.08 eV. 28 However, accurately measuring the offset is very difficult as seen from the wide spread (between 0.6 and 1.1 eV) of the reported experimental values.…”

Section: Alloys Ofmentioning

confidence: 99%

“…28 However, accurately measuring the offset is very difficult as seen from the wide spread (between 0.6 and 1.1 eV) of the reported experimental values. [21][22][23][24][25][26][27][28] 32 Band offsets for AlN, GaN, and AlGaN alloys are also important for device applications such as lasers and HEMTs. The variation in reported experimental VB offsets is, again, quite large [0.…”

Section: Alloys Ofmentioning

confidence: 99%

Hybrid functional investigations of band gaps and band alignments for AlN, GaN, InN, and InGaN

Moses

Miao

Yan

et al. 2011

The Journal of Chemical Physics

283

231

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Band gaps and band alignments for AlN, GaN, InN, and InGaN alloys are investigated using density functional theory with the with the Heyd-Scuseria-Ernzerhof {HSE06 [J. Heyd, G. E. Scuseria, and M. Ernzerhof, J. Chem. Phys. 134, 8207 (2003); 124, 219906 (2006)]} XC functional. The band gap of InGaN alloys as a function of In content is calculated and a strong bowing at low In content is found, described by bowing parameters 2.29 eV at 6.25% and 1.79 eV at 12.5%, indicating the band gap cannot be described by a single composition-independent bowing parameter. Valence-band maxima (VBM) and conduction-band minima (CBM) are aligned by combining bulk calculations with surface calculations for nonpolar surfaces. The influence of surface termination [(1100) mplane or (1120) a-plane] is thoroughly investigated. We find that for the relaxed surfaces of the binary nitrides the difference in electron affinities between m-and a-plane is less than 0.1 eV. The absolute electron affinities are found to strongly depend on the choice of XC functional. However, we find that relative alignments are less sensitive to the choice of XC functional. In particular, we find that relative alignments may be calculated based on Perdew-Becke-Ernzerhof [J. P. Perdew, K. Burke, and M. Ernzerhof, Phys. Rev. Lett. 134, 3865 (1996)] surface calculations with the HSE06 lattice parameters. For InGaN we find that the VBM is a linear function of In content and that the majority of the band-gap bowing is located in the CBM. Based on the calculated electron affinities we predict that InGaN will be suited for water splitting up to 50% In content.

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“…Chung-Lin Wu, 1,a͒ Hong-Mao Lee, 1 Cheng-Tai Kuo, 1 Chia-Hao Chen, 2 A method for studying heterojunction band lineups on the submicrometer scale is demonstrated by using synchrotron-radiation photoelectron microscopy and spectroscopy. In particular, an in situ sample cleavage technique is adopted here to reveal the cross-sectional, nonpolar a-plane face of InN / GaN heterojunction grown on Si͑111͒ along the polar −c axis with fully relaxed lattice structure, eliminating the polarization effects associated with the interface charge/dipole normal to the cleaved surface.…”

Section: Cross-sectional Scanning Photoelectron Microscopy and Spectrmentioning

confidence: 99%

Cross-sectional scanning photoelectron microscopy and spectroscopy of wurtzite InN∕GaN heterojunction: Measurement of “intrinsic” band lineup

Lee

Kuo

et al. 2008

Applied Physics Letters

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A method for studying heterojunction band lineups on the submicrometer scale is demonstrated by using synchrotron-radiation photoelectron microscopy and spectroscopy. In particular, an in situ sample cleavage technique is adopted here to reveal the cross-sectional, nonpolar a-plane face of InN∕GaN heterojunction grown on Si(111) along the polar −c axis with fully relaxed lattice structure, eliminating the polarization effects associated with the interface charge/dipole normal to the cleaved surface. The “intrinsic” valence band offset at the cleaved InN∕GaN heterojunction has been determined to be 0.78eV. Additionally, using known material parameters, the values of InN∕GaN conduction band offset and InN electron affinity are also estimated.

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Polarization-induced valence-band alignments at cation- and anion-polar InN∕GaN heterojunctions

Abstract: AlN and GaN epitaxial heterojunctions on 6H-SiC(0001): Valence band offsets and polarization fields

Cited by 37 publications

References 19 publications

Surface band bending and band alignment of plasma enhanced atomic layer deposited dielectrics on Ga- and N-face gallium nitride

Surface band bending and band alignment of plasma enhanced atomic layer deposited dielectrics on Ga- and N-face gallium nitride

Hybrid functional investigations of band gaps and band alignments for AlN, GaN, InN, and InGaN

Cross-sectional scanning photoelectron microscopy and spectroscopy of wurtzite InN∕GaN heterojunction: Measurement of “intrinsic” band lineup

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