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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, the authors apply principles of band gap engineering traditionally used at heterojunctions between conventional semiconductors to control the band offset between a single crystalline oxide and a semiconductor.
Abstract: The epitaxial growth of crystalline oxides on semiconductors provides a pathway to introduce new functionalities to semiconductor devices. Key to electrically coupling crystalline oxides with semiconductors to realize functional behavior is controlling the manner in which their bands align at interfaces. Here we apply principles of band gap engineering traditionally used at heterojunctions between conventional semiconductors to control the band offset between a single crystalline oxide and a semiconductor. Reactive molecular beam epitaxy is used to realize atomically abrupt and structurally coherent interfaces between SrZr$_{x}$Ti$_{1-x}$O$_3$ and Ge, in which the band-gap of the former is enhanced with Zr content $x$. We present structural and electrical characterization of SrZr$_{x}$Ti$_{1-x}$O$_3$-Ge heterojunctions for $x$ = 0.2 to 0.75 and demonstrate the band offset can be tuned from type-II to type-I, with the latter being verified using photoemission measurements. The type-I band offset provides a platform to integrate the dielectric, ferroelectric and ferromagnetic functionalities of oxides with semiconducting devices.
27 citations
TL;DR: In this article, the authors cross-correlate nanoscale spectral imaging by near-field scanning optical microscopy with a transmission electron microscopy analysis of the very same polytypic GaAs nanowire dispersed onto a Si wafer.
Abstract: III-V compound semiconductor nanowires are generally characterized by the coexistence of zincblende and wurtzite structures. So far, this polytypism has impeded the determination of the electronic properties of the metastable wurtzite phase of GaAs, which thus remain highly controversial. In an effort to obtain new insights into this topic, we cross-correlate nanoscale spectral imaging by near-field scanning optical microscopy with a transmission electron microscopy analysis of the very same polytypic GaAs nanowire dispersed onto a Si wafer. Thus, spatially resolved photoluminescence spectra could be unambiguously assigned to nanowire segments whose structure is known with lattice-resolved accuracy. An emission energy of 1.528 eV was observed from extended zincblende segments, revealing that the dispersed nanowire was under uniaxial strain presumably due to interaction with its supporting substrate. These crucial information and the emission energy obtained for extended pure wurtzite segments were used to perform envelope function calculations of zincblende quantum disks in a wurtzite matrix as well as the inverse structure. In these calculations, we varied the fundamental bandgap, the electron mass, and the band offset between zincblende and wurtzite GaAs. From this multi-parameter comparison with the experimental data, we deduced that the bandgap between the Γ8 conduction and A valence band ranges from 1.532 to 1.539 eV in strain-free wurtzite GaAs, and estimated values of 1.507 to 1.514 eV for the Γ7–A bandgap.
27 citations
TL;DR: In this article, the absorption spectra of a range of ZnSe-ZnS strained layer superlattices (SLSs) are compared with the photoluminescence spectra to reveal the effects of disorder.
27 citations
TL;DR: In this article, the energy band diagram of n-SnO2/n-Si HJ was constructed and the experimental data of the conduction band offset ΔEc and valence band offset ε = 0.55 eV and ΔEv = 1.8 eV were compared with theoretical values.
Abstract: Near-ideal n-SnO2/n-Si heterojunction band edge lineup has been investigated with aid of I–V and C–V measurements. The heterojunction was manufactured by rapid thermal oxidation of Sn metal films prepared by thermal evaporation technique on monocrystalline n-type silicon. The experimental data of the conduction band offset ΔEc and valence band offset ΔEc were compared with theoretical values. The band offset ΔEc = 0.55 eV and ΔEv = 1.8 eV obtained at 300 K. The energy band diagram of n-SnO2/n-Si HJ was constructed. C–V measurements depict that the junction was an abrupt type and the built-in voltage was determined from 1/C2–V plot.
27 citations
TL;DR: In this paper, the electronic structure of transition-metal (TM=Sc, Y, Zr, and Nb)-doped Al2O3 was investigated by x-ray photoemission spectroscopy (XPS) and X-ray absorption spectroscope (XAS).
Abstract: We have investigated the electronic structure of transition-metal (TM=Sc, Y, Zr, and Nb)-doped Al2O3 by x-ray photoemission spectroscopy (XPS) and x-ray absorption spectroscopy (XAS) In valence bands of these TM-doped Al2O3 measured by XPS, the highest occupied levels and the shapes of valence bands are almost unchanged from the pure alumina On the other hand, XAS spectra obtained at the oxygen K-edge show that Nb- and Zr-doped Al2O3 show localized d states in the bandgap below the conduction band minimum, while Y- and Sc-doped Al2O3 have d states inside the conduction band of the original Al2O3 This implies that Y- and Sc-doped Al2O3 will show little bandgap degradation and maintain the same band offset as silica at the Si interface, and can serve as promising candidates for an alternative gate oxide
27 citations