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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 paper, the microstructure and electrical properties of the PECVD-enhanced chemical-vapor deposition (PECVD) alloys were reviewed and the authors explained significant quantitative differences between the carrier transport properties of μc-Si and μcSi,C alloys in terms of a band offset model for the interfacial potential steps between the amorphous and crystalline constituents of these material systems.
Abstract: The microstructure and electrical properties of μc-Si and μc-Si,C prepared by remote plasma-enhanced chemical-vapor deposition, PECVD, are reviewed. The microstructure has been characterized by transmission electron microscopy, TEM, infrared, IR, absorption and Raman scattering. The electrical properties were characterized by temperature-dependent dark-conductivity measurements. These studies have explained significant quantitative differences between the carrier transport properties of μc-Si and μc-Si,C alloys in terms of a band offset model for the interfacial potential steps between the amorphous and crystalline constituents of these material systems.

18 citations

Journal ArticleDOI
TL;DR: In this article, the authors measured the band offsets at the interfaces of n- and p-type InP ((100) and (111)A) and atomic-layer-deposited (ALD) Al2O3 were measured with internal photoemission and spectroscopic ellipsometry.
Abstract: Band offsets at the interfaces of n- and p-type InP ((100) and (111)A) and atomic-layer-deposited (ALD) Al2O3 were measured with internal photoemission and spectroscopic ellipsometry. Similarly, the band offsets at the interface of semi-insulating InP (100) and ALD HfO2 were also determined. The barrier between the top of InP valence band (VB) and the bottom of Al2O3 conduction band (CB) is found to be 3.44 eV for p-type material and 3.53 eV for n-type. The photoemission thresholds are found to be sensitive to the annealing conditions, and blue shifts are observed after annealing. The offsets from InP valence band to the HfO2 conduction band for the HfO2/InP stack are found to be 3.89 eV, and we observed an increase of 60 meV if the InP surface is passivated.

18 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of Al and La incorporation on the electronic properties of the interface in the SiO{}_{2}$/HfO${}_{ 2}$ high-k gate stacks was examined using density functional theory.
Abstract: Using density functional theory (DFT) we examine the effect of Al and La incorporation on the electronic properties of the interface in the SiO${}_{2}$/HfO${}_{2}$ high-k gate stacks recently introduced into the advanced modern field effect transistors (FETs). We show that La and Al doping have opposite effects on the band alignment at the SiO${}_{2}$/HfO${}_{2}$ interface: while the Al ions, which substitute preferentially for Si in the SiO${}_{2}$ layer, promote higher effective work function (EWF) values, the substitution of La for Hf decreases EWF. The analysis of the electronic structure of the doped interface suggests a simple relation between the electronegativity of the doping metal, screening properties of the interfacial layer, and the band offset, which allows predicting qualitatively the effect of the high-k gate stack doping with a variety of metals on its EWF.

18 citations

Journal ArticleDOI
TL;DR: In this article, the authors calculate the band offset of CZTS(Se) with CdS and find that increasing temperature significantly enhances the spike-type offset, and use these to estimate the upper limit of electron and hole mobilities based on optic phonon Frohlich scattering.
Abstract: The efficiencies of solar cells based on kesterite Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) are limited by a low open-circuit voltage due to high rates of non-radiative electron-hole recombination. To probe the origin of this bottleneck, we calculate the band offset of CZTS(Se) with CdS, confirming a weak spike of 0.1 eV for CZTS/wurtzite-CdS and a strong spike of 0.4 eV for CZTSe/wurtzite-CdS. We also consider the effects of temperature on the band alignment, finding that increasing temperature significantly enhances the spike-type offset. We further resolve an outstanding discrepancy between the measured and calculated phonon frequencies for the kesterites, and use these to estimate the upper limit of electron and hole mobilities based on optic phonon Frohlich scattering, which uncovers an intrinsic asymmetry with faster (minority carrier) electron mobility.

18 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used first-principles calculations with different levels of computational methods and functionals within the density functional theory to investigate the long-standing band gap problem for SnO2.
Abstract: From the recent experimentally observed conduction band offset and previously reported band gaps, one may deduce that the valence band offset between rutile SnO2 and TiO2 is around 1 eV, with TiO2 having a higher valence band maximum. This implication sharply contradicts the fact that the two compounds have the same rutile structure and the Γ3+ VBM state is mostly an oxygen p state with a small amount of cation d character, thus one would expect that SnO2 and TiO2 should have small valence band offset. If the valence band offset between SnO2 and TiO2 is indeed small, one may question the correctness of the previously reported band gaps of SnO2 and TiO2. In this paper, using first-principles calculations with different levels of computational methods and functionals within the density functional theory, we reinvestigate the long-standing band gap problem for SnO2. Our analysis suggests that the fundamental band gap of SnO2 should be similar to that of TiO2, i.e., around 3.0 eV. This value is significantly smaller than the previously reported value of about 3.6 eV, which can be attributed as the optical band gap of this material. Similar to what has been found in In2O3, the discrepancy between the fundamental and optical gaps of SnO2 can be ascribed to the inversion symmetry of its crystal structure and the resultant dipole-forbidden transitions between its band edges. Our results are consistent with most of the optical and electrical measurements of the band gaps and band offset between SnO2 and TiO2, thus provide new understanding of the band structure and optical properties of SnO2. Experimental tests of our predictions are called for.

18 citations


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