Topic
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, the authors examined the band offsets of selected zinc-blende, wurtzite, and mixed zincblende/wurtzites GaN/AlN, GaN-SiC, and AlN/SiC heterostructures and their dependence on various structural and chemical properties of the interfaces.
Abstract: From first principles we have examined the band offsets of selected zinc-blende, wurtzite, and mixed zinc-blende/wurtzite GaN/AlN, GaN/SiC, and AlN/SiC heterostructures, and their dependence on various structural and chemical properties of the interfaces. Contrary to the case of the conventional, small-gap, semiconductor heterojunctions, local atomic interfacial relaxation has a major influence on the offsets of the polar heterovalent nitride systems. However, provided this effect is taken into account, the band-offset dependence on interface orientation, strain, and heterovalency can still be qualitatively explained using linear-response-theory schemes. We also show that a change in the band-gap discontinuity resulting from a cubic (111) to hexagonal (0001) polytype transformation in nitride heterostructures will be selectively found in the conduction-band offset.
53 citations
TL;DR: In this paper, a GaAs(1-x)Sbx/GaAs strained-layer multiple quantum wells have been grown by molecular-beam epitaxy and characterized by room-temperature photoreflectance (PR).
Abstract: GaAs(1-x)Sbx/GaAs strained-layer multiple quantum wells have been grown by molecular-beam epitaxy and characterized by room-temperature photoreflectance (PR). The PR spectra denote that high-quality layers can be grown in the GaAs(1-x)Sbx/GaAs system. The method for determining the band offset Q(vh) is discussed in this strained-layer system.
53 citations
TL;DR: In this paper, a heteroquantum-dots (HQD) model for hydrogenated nanocrystalline silicon films (nc•Si:H) is proposed, where the activated electrons in the quantum dots conduct via quantum tunneling through the interface barriers.
Abstract: A heteroquantum‐dots (HQD) model for hydrogenated nanocrystalline silicon films (nc‐Si:H) is proposed. The main features of our model are as follows. (i) the nanocrystalline grains and the amorphous counterparts in which they are embedded have very different band gap and band structures. As a result, they form heterojunctionlike structures in the interface regions, where the band offset effects dramatically reduce the activation energy and the grains act like quantum dots. (ii) In the presence of an external field, the activated electrons in the quantum dots conduct via quantum tunneling through the interface barriers. By means of the HQD model, we have identified the conduction of nc‐Si:H as a thermal‐assisted tunneling process. Our results show that there are two distinct regimes for the conductivity of nc‐Si:H: (i) the low‐temperature regime, where there is a simple activation energy ΔE; (ii) the high‐temperature regime, where ΔE is effectively enhanced by the temperature effect of the electronic tunne...
53 citations
TL;DR: In this article, X-ray photoelectron spectroscopy was used to measure the energy discontinuity in the valence band (ΔEv) of MgO∕GaN heterostructures.
Abstract: MgO is a promising gate dielectric and surface passivation film for GaN transistors but little is known of the band offsets in the MgO∕GaN system. X-ray photoelectron spectroscopy was used to measure the energy discontinuity in the valence band (ΔEv) of MgO∕GaN heterostructures in which the MgO was grown by rf plasma-assisted molecular beam epitaxy on top of thick GaN templates on sapphire substrates. A value of ΔEv=1.06±0.15eV was obtained by using the Ga 3d energy level as a reference. Given the experimental band gap of 7.8eV for the MgO, this would indicate a conduction band offset ΔEC of 3.30eV in this system.
53 citations
TL;DR: In this article, the correlation between the threshold shift and strained-Si layer thickness was investigated based on device simulations, and a larger threshold distribution was observed in devices fabricated with a strained layer thickness comparable to the depletion depth.
Abstract: Due to the offset in the valence band, strained-Si nMOSFETs exhibit a -100 mV threshold shift and 4% degradation of the subthreshold slope per each 10% increase of Ge content in the relaxed SiGe layer. The correlation between the threshold shift and strained layer thickness is investigated based on device simulations. In a certain range of the strained-Si layer thickness, the threshold and subthreshold slope change gradually, posing a concern of larger device parameter variation. A larger threshold distribution is observed in devices fabricated with a strained layer thickness comparable to the depletion depth.
53 citations