Surface states and electronic structure of polar and nonpolar InN – An <i>in situ</i> photoelectron spectroscopy study

Eisenhardt, Anja; Krischok, S.; Himmerlich, Marcel

doi:10.1063/1.4810074

Cited by 26 publications

(21 citation statements)

References 26 publications

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“…The similar result was obtained for the InN surface using photon excitation energy of 90 eV [24]. In addition to that XPS studies reveal the valence band photoemission with two clearly defined maxima [11,12,[16][17][18][19][20][21][22][23][24][25]. The difference between UPS and XPS spectra can be related to the significant contribution in UPS results of both the surface and near surface regions.…”

Section: Methodssupporting

confidence: 83%

“…The difference between UPS and XPS spectra can be related to the significant contribution in UPS results of both the surface and near surface regions. The shape and the bandwidth of the valence band spectrum coincide well with ones that are obtained previously by UPS [16][17][18][19][20][21][22][23][24]. The unresolved In 4d peak (spin-orbit split In 4d 3/2 and In 4d 5/2) is observed at binding energy of 15.1 eV with respect to E VBM .…”

Section: Methodssupporting

confidence: 81%

“…A weakly structured photoemission spectrum of valence band was found at the excitation energies of hν¼90 eV [24] and 150 eV [25]. In this case the surface contribution to the spectrum in the valence band region is more significant than that in the case of the Al K α excitation [11,12,[15][16][17][18][19][20][21]. A difference in the shape of the valence band spectrum can be caused by various contributions to both the bulk and the surface region.…”

Section: Introductionmentioning

confidence: 89%

“…The valence band spectra of wurtzite InN samples were studied by XPS and UPS [11,12,[15][16][17][18][19][20][21][22][23][24][25]. The XPS valence band spectrum consists usually of a broad band with two maxima at 1-3 eV and at 5-6 eV below the E VBM .…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Synchrotron radiation photoemission study of the ultrathin Cs/InN interface

Benemanskaya

Lapushkin

Timoshnev

et al. 2015

Solid State Communications

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Section: Methodssupporting

confidence: 83%

Section: Methodssupporting

confidence: 81%

Section: Introductionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Synchrotron radiation photoemission study of the ultrathin Cs/InN interface

Benemanskaya

Lapushkin

Timoshnev

et al. 2015

Solid State Communications

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“…The strong reduction of the emission intensity at 3.1 eV is a clear indication that this structure refers to an occupied surface state which is saturated by small amounts of adsorbing atoms or molecules, comparable to surface states close to the VB edge of other III-nitride surfaces. 21 By linear extrapolation of the XPS VB edge, the VBM of the as grown GaN(1-100) surface is estimated to be at 2.7 eV, hence closer at the Fermi energy (E F ) than we have found for the Ga-polar surface (2.9-3.0 eV). 22,23 The upward band bending (V bb ) for the GaN(1-100) surface amounts to 0.6 eV as schematically visualized in Fig.…”

mentioning

confidence: 60%

Confirmation of intrinsic electron gap states at nonpolar GaN(1-100) surfaces combining photoelectron and surface optical spectroscopy

Himmerlich¹,

Eisenhardt²,

Shokhovets³

et al. 2014

Applied Physics Letters

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The electronic structure of GaN(1-100) surfaces is investigated in-situ by photoelectron spectroscopy (PES) and reflection anisotropy spectroscopy (RAS). Occupied surface states 3.1 eV below the Fermi energy are observed by PES, accompanied by surface optical transitions found in RAS around 3.3 eV, i.e., below the bulk band gap. These results indicate that the GaN(1-100) surface band gap is smaller than the bulk one due to the existence of intra-gap states, in agreement with density functional theory calculations. Furthermore, the experiments demonstrate that RAS can be applied for optical surface studies of anisotropic crystals. V C 2014 AIP Publishing LLC.

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Axial InN/InGaN Nanorod Array Heterojunction Photodetector with Ultrafast Speed

Chai

Liu

Chen

et al. 2023

Adv Elect Materials

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requires the photodetection wavelength of the photo detector could match the source wavelength. [4][5][6] In this regard, the bandgap tunable semiconductor and its fabricated photodetector with fast response speed have become a research hotspot. [7][8][9] InGaN semiconductors can achieve wavelength-selective absorption owning to their tunable bandgap (0.65-3.4 eV), which is adjusted by varying the composition of Indium (In). [10][11][12] Thanks to the development of semiconductor industry technology, the InGaN photodetector with PIN and integrated structure has been used in visible light communication systems. [13][14][15] However, the above InGaN-based ultrafast photodetector heavily relies on expensive, slow, complex material growth and chip preparation processes. [16] Accordingly, the development of a simple-structured photodetector with a fast response speed is urgently needed. [17] The photodetector with simple heterojunction demonstrates fast photodetection owing to the built-in electric field to facilitate carrier separation and transport. [18,19] Among the III-nitrides materials, on account of the high electron mobility (4400 cm 2 V −1 s −1 ), the InN semiconductors are widely used to fabricate fast photodetectors. [20,21] Regarding the mentioned above, the InN/InGaN heterojunction is considered a promising candidate for preparing a fast photodetector. This is well known that the high-performance photodetector composed of wide band gap materials lies on top of the narrow band gap materials, thus the InGaN should be grown on the top of InN. [22] However, this InN/InGaN heterojunction cannot be realized due to the growth temperature of InGaN is higher than the dissociation temperature of InN.The dilemma above might be solved by introducing 1D InN nanorod array (NRA) to InGaN films, which could not only relax the strain to form defect-free lattice-mismatched heterostructures but also break through the material arrangement limit of the bandgap. [23,24] Previous research has reported an InN/InGaN heterojunction with the structure of InN NRA on the InGaN epilayer and applied it to optoelectronic devices. [25,26] Nevertheless, this method needs phase-separated from In-rich InGaN buffer as the nucleation sites, which will cause the diameter uniformity of these structures to be poor. The axial heterojunction structure is an effective strategy, on one hand, the diameter uniformity of InN could be controlled, on the other hand, the 1D geometry could confine carriers separation in a very small NRA Due to wavelength-selective characteristics, the InGaN-based photodetectors show bright prospects in visible light communication and fast imaging system. However, the application of InGaN photodetectors with simple structures is limited in the above field owing to the slow response speed. Herein, an ultrafast photodetector based on axial InN/InGaN nanorod array (NRA) heterojunction is prepared through a self-catalytic high (930 °C) and low (400 °C) temperature two-step growth method by molecular beam epitaxy (MBE). The perf...

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Surface states and electronic structure of polar and nonpolar InN – An in situ photoelectron spectroscopy study

Cited by 26 publications

References 26 publications

Synchrotron radiation photoemission study of the ultrathin Cs/InN interface

Synchrotron radiation photoemission study of the ultrathin Cs/InN interface

Confirmation of intrinsic electron gap states at nonpolar GaN(1-100) surfaces combining photoelectron and surface optical spectroscopy

Axial InN/InGaN Nanorod Array Heterojunction Photodetector with Ultrafast Speed

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