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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: Density functional theory calculations show that the presence of a defective α-Ga2O3-x thin layer in the GaN and sapphire heterostructure remarkably reduces the band offset between the α- Ga2O1-x conduction band and theGaN valence band, thereby exerting a significant influence on the conductivity enhancement of the interface.
Abstract: An electrically degenerate layer deteriorates the optoelectric performance of a wide band gap semiconductor grown on an insulator substrate. This detrimental effect can be passively avoided by using a buffer layer to harbor various lattice defects. However, the longstanding scientific questions regarding the microscopic origin of the degenerate interface layer and the effect of local changes in the atomic structure and chemical environment at an interface on the functionality of a desired film have remained unanswered. Moreover, this is key information for the development of ultrathin optoelectronic devices. In this study, we discuss the direct observation of a degenerate interface phase at the GaN/sapphire interface on an atomic scale. By combining high-resolution transmission electron microscopy and electron energy loss spectroscopy, we detect the presence of an ultrathin (∼6.5 A) α-Ga2O3-x layer near the GaN/sapphire interface, which is subjected to ∼4.5% biaxial compressive strain and contains many oxygen vacancies. Density functional theory calculations show that the presence of a defective α-Ga2O3-x thin layer in the GaN and sapphire heterostructure remarkably reduces the band offset between the α-Ga2O3-x conduction band and the GaN valence band, thereby exerting a significant influence on the conductivity enhancement of the interface. Our results provide an unprecedented integrated picture of the degenerate interface phenomenon on an atomic scale, which would evolve the fundamental understanding about a wide band gap semiconductor heterostructure system.

14 citations

Journal ArticleDOI
TL;DR: In this article, high-resolution atomic force microscopy and scanning electrochemical microscopy are used to investigate the electron transfer behavior of layered MoS2 flakes in organic solutions, offering insights on the electronic band alignment at the solid-liquid interface.
Abstract: Layered MoS2 is considered as one of the most promising two-dimensional photocatalytic materials for hydrogen evolution and water splitting; however, the electronic structure at the MoS2-liquid interface is so far insufficiently resolved. Measuring and understanding the band offset at the surfaces of MoS2 are crucial for understanding catalytic reactions and to achieve further improvements in performance. Herein, the heterogeneous charge transfer behavior of MoS2 flakes of various layer numbers and sizes is addressed with high spatial resolution in organic solutions using the ferrocene/ferrocenium (Fc/Fc+) redox pair as a probe in near-field scanning electrochemical microscopy, i.e. in close nm probe-sample proximity. Redox mapping reveals an area and layer dependent reactivity for MoS2 with a detailed insight into the local processes as band offset and confinement of the faradaic current obtained. In combination with additional characterization methods, we deduce a band alignment occurring at the liquid-solid interface. Here, high-resolution atomic force microscopy and scanning electrochemical microscopy are used to investigate the electron transfer behaviour of layered MoS2 flakes in organic solutions, offering insights on the electronic band alignment at the solid-liquid interface.

14 citations

Journal ArticleDOI
TL;DR: In this paper, the influence of contact materials on the electrical characteristics of field effect transistors made from poly(3-hexylthiophene) with short-channel lengths of 80 nm was investigated.
Abstract: The influence of contact materials on the electrical characteristics of field-effect transistors made from poly(3-hexylthiophene) with short-channel lengths of 80 nm is investigated. The thermally activated output current indicates the presence of a potential barrier at the electrode/organic contact. The barrier is not related to surface oxide and results in non-linear junction characteristics with activation voltage that can be only partially controlled via the work function of the contact metal. A Schottky contact at the metal/polymer interface arises from the band offset of the two materials and from interfacial dipole layers. Transistor operation with on/off ratio over 103 is achieved with five different electrode materials.

14 citations

Journal ArticleDOI
TL;DR: In this paper, a temperature dependent magneto-optical investigation of the valence band offset between HgTe and CdTe was conducted in a wide regime from liquid helium to nearly room temperature.

14 citations

Journal ArticleDOI
TL;DR: In this paper, the energy-band nonparabolicity of both conduction and valence bands was investigated and the required value of the ratio of the conduction-band and the valence-band discontinuities was found to be close to 2/3 in agreement with the value found by other methods.
Abstract: Energy levels in InP/Ga0.47In0.53As quantum wells are calculated after reformulating the energy‐dependent effective mass to be used for taking into account the energy‐band nonparabolicity of both constituents. The required value of the ratio of the conduction‐band and valence‐band discontinuities is found to be close to 2/3, in agreement with the value found by other methods. The value of the nonparabolicity factor is also found to be the same as that used in earlier transport studies.

14 citations


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