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: The SnO2/Si heterojunction shows a stable, repeatable and broadband photoresponse from 365 nm to 980 nm and the photosensitivity and detectivity are an order of magnitude higher than that of 2D material based heterojunctions such as (Bi2Te3)/Si and MoS2/graphene.
Abstract: The SnO2/Si heterojunction possesses a large band offset and it is easy to control the transportation of carriers in the SnO2/Si heterojunction to realize high-response broadband detection. Therefore, we investigated the potential of the SnO2 nanoparticle thin film/SiO2/p-Si heterojunction for photodetectors. It is demonstrated that this heterojunction shows a stable, repeatable and broadband photoresponse from 365 nm to 980 nm. Meanwhile, the responsivity of the device approaches a high value in the range of 0.285-0.355 A W-1 with the outstanding detectivity of ∼2.66 × 1012 cm H1/2 W-1 and excellent sensitivity of ∼1.8 × 106 cm2 W-1, and its response and recovery times are extremely short (<0.1 s). This performance makes the device stand out among previously reported oxide or oxide/Si based photodetectors. In fact, the photosensitivity and detectivity of this heterojunction are an order of magnitude higher than that of 2D material based heterojunctions such as (Bi2Te3)/Si and MoS2/graphene (photosensitivity of 7.5 × 105 cm2 W-1 and detectivity of ∼2.5 × 1011 cm H1/2 W-1). The excellent device performance is attributed to the large Fermi energy difference between the SnO2 nanoparticle thin film and Si, SnO2 nanostructure, oxygen vacancy defects and thin SiO2 layer. Consequently, practical highly-responsive broadband PDs may be actualized in the future.
35 citations
TL;DR: In this article, the authors used x-ray photoelectron spectroscopy to measure the valence band offset in situ for strained Si/Ge (100) heterojunctions and for AlSb/ZnTe (100), grown by molecular-beam epitaxy.
Abstract: We have used x-ray photoelectron spectroscopy to measure the valence band offset in situ for strained Si/Ge (100) heterojunctions and for AlSb/ZnTe (100) heterojunctions grown by molecular-beam epitaxy. For the Si/Ge system, Si 2p and Ge 3d core level to valence band edge binding energies and Si 2p to Ge 3d core level energy separations were measured as functions of strain, and strain configurations in all samples were determined using x-ray diffraction. Our measurements yield valence band offset values of 0.83±0.11 eV and 0.22±0.13 eV for Ge on Si (100) and Si on Ge (100), respectively. If we assume that the offset between the weighted averages of the light-hole, heavy-hole, and spin-orbit valence bands in Si and Ge is independent of strain, we obtain a discontinuity in the average valence band edge of 0.49±0.13 eV. For the AlSb/ZnTe (100) heterojunction system, we obtain a value of –0.42±0.07 eV for the valence band offset. Our data also suggest that an intermediate compound, containing Al and Te, is formed at the AlSb/ZnTe (100) interface.
35 citations
TL;DR: In this paper, 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 SrZrxTi1-xO3 and Ge, in which the band gap of the former is enhanced with Zr content x. We present structural, electrical and photoemission characterization of SrZrxTi1-xO33-Ge heterojunctions for x = 0.2 to 0.75 and demonstrate the band offset can be tuned from type-II to type-I. The type-I band offset provides a platform to integrate the dielectric, ferroelectric and ferromagnetic functionalities of oxides with semiconducting devices.
34 citations
DSM1
TL;DR: In this article, the authors present the results of valence band studies by soft X-ray photoemission spectroscopy on ex situ prepared, ultra-thin Hf-oxide layers on 0.7 nm SiO 2 /Si.
34 citations
TL;DR: In this article, the authors measured the valence band offset at the interface between the BaSi2 and the a-Si to understand the carrier transport properties by the determination of the band offset.
Abstract: The 730 nm-thick undoped BaSi2 films capped with 5 nm-thick amorphous Si (a-Si) intended for solar cell applications were grown on Si(111) by molecular beam epitaxy. The valence band (VB) offset at the interface between the BaSi2 and the a-Si was measured by hard x-ray photoelectron spectroscopy to understand the carrier transport properties by the determination of the band offset at this heterointerface. We performed the depth-analysis by varying the take-off angle of photoelectrons as 15°, 30°, and 90° with respect to the sample surface to obtain the VB spectra of the BaSi2 and the a-Si separately. It was found that the barrier height of the a-Si for holes in the BaSi2 is approximately −0.2 eV, whereas the barrier height for electrons is approximately 0.6 eV. This result means that the holes generated in the BaSi2 layer under solar radiation could be selectively extracted through the a-Si/BaSi2 interface, promoting the carrier separation in the BaSi2 layer. We therefore conclude that the a-Si/BaSi2 inte...
34 citations