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Band offset

About: Band offset is a research topic. Over the lifetime, 2446 publications have been published within this topic receiving 53450 citations.


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TL;DR: In this article, a band-aligned superlattice laser is proposed which uses the intersubband optical transition in a bandaligned super lattice, where the miniband discontinuity within the conduction of valence band functions as a band offset in the heterojunction structure.
Abstract: A novel infrared laser is proposed which uses the intersubband optical transition in a band‐aligned superlattice. In this band‐aligned superlattice laser, the miniband discontinuity within the conduction of valence band functions as a band offset in the heterojunction structure, and the population inversion is achieved by current injection as in the conventional heterojunction laser. It is more flexible than a heterojunction laser of a quantum well laser since one may tailor the bandwidth and band structures as well as the band gap of the minibands. Also indirect band‐gap materials like Si and Ge can be used for lasing in the intersubband transitions. The intersubband optical transition is similar to an atomic two‐level system which exhibits low threshold current, and a gain coefficient with weak temperature dependence and a narrow spectrum which is determined only by the line‐shape function. These special features make the band‐aligned superlattice laser competitive with and perhaps superior to the quantum well dot laser which is not presently feasible.

61 citations

Journal ArticleDOI
TL;DR: In this article, the authors measured the valence band offset at the ZnO/Zn0.85Mg0.15O heterojunction grown by plasma-assisted molecular beam epitaxy.
Abstract: X-ray photoelectron spectroscopy was used to measure the valence band offset at the ZnO/Zn0.85Mg0.15O heterojunction grown by plasma-assisted molecular beam epitaxy. The valence band offset (ΔEV) is determined to be 0.13 eV. According to the experimental band gap of 3.68 eV for the Zn0.85Mg0.15O, the conduction band offset (ΔEC) in this system was calculated to be 0.18 eV. The ΔEc:ΔEv in ZnO/Zn0.85Mg0.15O heterojunction was estimated to be 3:2.

61 citations

Journal ArticleDOI
TL;DR: In this article, the interface region between Ga-face n-type GaN and Al2O3 dielectric was investigated by X-ray photoelectron spectroscopy (XPS), and an increase in the Ga-O to Ga-N bond intensity ratio following Al 2O3 deposition implies that the growth of an interfacial gallium suboxide (GaOx) layer occurred during the ALD process.
Abstract: The interface region between Ga-face n-type GaN and Al2O3 dielectric (achieved via atomic-layer deposition or ALD) is investigated by X-ray photoelectron spectroscopy (XPS). An increase in the Ga-O to Ga-N bond intensity ratio following Al2O3 deposition implies that the growth of an interfacial gallium sub-oxide (GaOx) layer occurred during the ALD process. This finding may be ascribed to GaN oxidation, which may still happen following the reduction of a thin native GaOx by trimethylaluminum (TMA) in the initial TMA-only cycles. The valence band offset between GaN and Al2O3, obtained using both core-level and valence band spectra, is found to vary with the thickness of the deposited Al2O3. This observation may be explained by an upward energy band bending at the GaN surface (due to the spontaneous polarization induced negative bound charge on the Ga-face GaN) and the intrinsic limitation of the XPS method for band offset determination.

61 citations

Journal ArticleDOI
TL;DR: In this article, the authors described the method of cross-sectional scanning tunnelling microscopy (STM) for the observation of structural features on an atomic scale, including alloy clustering, interface roughness, band offsets, quantum subbands and point defects.
Abstract: The method of cross-sectional scanning tunnelling microscopy (STM) is described. Illustrative examples are given of studies of III-V semiconductor systems, including AlxGa1-xAs/GaAs superlattices, InAs/GaSb superlattices and low-temperature-grown GaAs. Physical properties studied include alloy clustering, interface roughness, band offsets, quantum subbands and point defects. In each case, STM permits the observation of structural features on an atomic scale. The associated electronic spectroscopy for states a few eV on either side of the Fermi level can be determined. Such information is relevant for the operation of devices constructed from these layered semiconductor systems.

61 citations

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate the modification of the CZTSSe absorber/CdS buffer interface following the deposition of 1'nm-thick Al2O3 layers by atomic layer deposition (ALD) near room temperature.
Abstract: The greatest challenge for improving the power conversion efficiency of Cu2ZnSn(S,Se)4 (CZTSSe)/CdS/ZnO thin film solar cells is increasing the open circuit voltage (VOC). Probable leading causes of the VOC deficit in state-of-the-art CZTSSe devices have been identified as bulk recombination, band tails, and the intertwined effects of CZTSSe/CdS band offset, interface defects, and interface recombination. In this work, we demonstrate the modification of the CZTSSe absorber/CdS buffer interface following the deposition of 1 nm-thick Al2O3 layers by atomic layer deposition (ALD) near room temperature. Capacitance-voltage profiling and quantum efficiency measurements reveal that ALD-Al2O3 interface modification reduces the density of acceptor-like states at the heterojunction resulting in reduced interface recombination and wider depletion width. Indications of increased VOC resulting from the modification of the heterojunction interface as a result of ALD-Al2O3 treatment are presented. These results, while ...

61 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202336
202267
202178
202085
201980
201882