Electron accumulation at InN/AlN and InN/GaN interfaces

Veal, T. D.; Piper, Louis F. J.; Mahboob, Imran; Lu, Hai; Schaff, W. J.; McConville, Christopher F

doi:10.1002/pssc.200461418

Cited by 21 publications

(17 citation statements)

References 15 publications

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“…In an otherwise bulk p-type InN sample, as in the case shown in Fig. 2b, similar, highly degenerate n-type inversion layers are expected on the surface as well as at the InN/substrate or InN/buffer-layer interface [3][4][5][6][7][8]. Because these layers are degenerate (n ∼ 10 In contrast, the samples with more Mg (e.g.…”

Section: Electrical and Thermoelectric Measurements A Resultsmentioning

confidence: 52%

“…This indicates the presence of a thicker layer of n-type conducting material, likely due to the combined effects of self-compensation and increased extended defect density with large Mg concentrations as well as interface-related charge [6,61]. Using Eq.…”

Section: Electrical and Thermoelectric Measurements A Resultsmentioning

confidence: 99%

“…InN has a very large electron affinity, and undoped InN films persistently exhibit n-type conductivity and a metallic surface accumulation layer due to pinning of the Fermi level above the conduction band edge [3][4][5][6][7][8]. Mg has been used as a p-type dopant, but the surface pinning in this case creates an n-type surface inversion layer which complicates Hall effect measurements and prevents direct electrical contact to any p-type material below.…”

Section: Introductionmentioning

confidence: 99%

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Hole transport and photoluminescence in Mg-doped InN

Miller

Ager

Smith

et al. 2010

Journal of Applied Physics

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Hole conductivity and photoluminescence were studied in Mg-doped InN films grown by molecular beam epitaxy. Because surface electron accumulation interferes with carrier type determination by electrical measurements, the nature of the majority carriers in the bulk of the films was determined using thermopower measurements. Mg concentrations in a "window" from ca. 3 × 10 17 to 1 × 10 19 cm −3 produce hole-conducting, p-type films as evidenced by a positive Seebeck coefficient. This conclusion is supported by electrolyte-based capacitance voltage measurements and by changes in the overall mobility observed by Hall effect, both of which are consistent with a change from surface accumulation on an n-type film to surface inversion on a p-type film. The observed Seebeck coefficients are understood in terms of a parallel conduction model with contributions from surface and bulk regions. In partially compensated films with Mg concentrations below the window region, two peaks are observed in photoluminescence at 672 meV and at 603 meV. They are attributed to band-to-band and band-to-acceptor transitions, respectively, and an acceptor binding energy of ∼70 meV is deduced. In hole-conducting films with Mg concentrations in the window region, no photoluminescence is observed; this is attributed to electron trapping by deep states which are empty for Fermi levels close to the valence band edge. * Corresponding author: JWAger@lbl.gov

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Section: Electrical and Thermoelectric Measurements A Resultsmentioning

confidence: 52%

Section: Electrical and Thermoelectric Measurements A Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hole transport and photoluminescence in Mg-doped InN

Miller

Ager

Smith

et al. 2010

Journal of Applied Physics

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“…9,27,28 A downward band bending of ∼0.6-0.7 eV was observed, associated with donor-type surface states with a density of about 2.5(±0.2) ×10 13 cm −2 , and a surface Fermi level of about 1.6±0.1 eV above the VBM. 9,28 Our survey indicates that even though a variety of experimental results are available, a 4 number of conflicting results have been reported and a consistent interpretation is lacking.…”

Section: Survey Of Experimental Resultsmentioning

confidence: 98%

Microscopic origins of surface states on nitride surfaces

Walle

Segev

2007

Journal of Applied Physics

266

208

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We report a systematic and comprehensive computational study of the electronic structure of GaN and InN surfaces in various orientations, including the polar c plane as well as the nonpolar a and m planes. Surface band structures and density-of-states plots show the energetic position of surface states, and by correlating the electronic structure with atomistic information we are able to identify the microscopic origins of each of these states. Fermi-level pinning positions are identified, depending on surface stoichiometry and surface polarity. For polar InN we find that all the surface states are located above the conduction-band minimum, and explain the source of the intrinsic electron accumulation that has been universally observed on InN surfaces.

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“…It is now understood that the location of the Fermi stabilization energy 3 at 0.9 eV above the conduction band edge causes the surface Fermi level to be pinned above the conduction band by donor defects at the film interface and surface. These n-type surface electron accumulation layers (SEALs) have made it impossible to directly measure bulk electrical transport properties of p-type InN [4][5][6] .…”

Section: Introductionmentioning

confidence: 99%