Optical characterization of type-I to type-II band alignment transition in GaAs/AlxGa1−xAs quantum rings grown by droplet epitaxy

Efficient light harvesting devices need to combine strong absorption in the visible spectral range with efficient ultrafast charge separation. These features commonly occur in novel ultimately thin van der Waals heterostructures with type II band alignment. Recently, ultrafast charge separation was also observed in monolayer WS2/graphene heterostructures with type I band alignment. Here we use time- and angle-resolved photoemission spectroscopy to show that ultrafast charge separation also occurs at the interface between bilayer WS2 and graphene indicating that the indirect band gap of bilayer WS2 does not affect the charge transfer to the graphene layer. The microscopic insights gained in the present study will turn out to be useful for the design of novel optoelectronic devices.

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Type II Band Alignment inSi1−xGex/Si(001)Quantum Wells: The Ubiquitous Type I Luminescence Results from Band Bending

Physical Review Letters ◽

10.1103/physrevlett.79.269 ◽

1997 ◽

Vol 79 (2) ◽

pp. 269-272 ◽

Cited By ~ 107

Author(s):

M. L. W. Thewalt ◽

D. A. Harrison ◽

C. F. Reinhart ◽

J. A. Wolk ◽

H. Lafontaine

Keyword(s):

Quantum Wells ◽

Band Alignment ◽

Type I ◽

Type Ii ◽

Band Bending

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PN/PAs-WSe2 van der Waals heterostructures for solar cell and photodetector

Scientific Reports ◽

10.1038/s41598-020-73152-7 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Xinyi Zheng ◽

Yadong Wei ◽

Kaijuan Pang ◽

Ngeywo Kaner Tolbert ◽

Dalin Kong ◽

...

Keyword(s):

Refractive Index ◽

Solar Cells ◽

Negative Refractive Index ◽

Wide Spectrum ◽

Van Der Waals ◽

Band Alignment ◽

Ultraviolet Region ◽

Type I ◽

Type Ii ◽

Van Der Waals Heterostructures

Abstract By first-principles calculations, we investigate the geometric stability, electronic and optical properties of the type-II PN-WSe2 and type-I PAs-WSe2 van der Waals heterostructures(vdWH). They are p-type semiconductors with indirect band gaps of 1.09 eV and 1.08 eV based on PBE functional respectively. By applying the external gate field, the PAs-WSe2 heterostructure would transform to the type-II band alignment from the type-I. With the increasing of magnitude of the electric field, two heterostructures turn into the n-type semiconductors and eventually into metal. Especially, PN/PAs-WSe2 vdWH are both high refractive index materials at low frequencies and show negative refractive index at high frequencies. Because of the steady absorption in ultraviolet region, the PAs-WSe2 heterostructure is a highly sensitive UV detector material with wide spectrum. The type-II PN-WSe2 heterostructure possesses giant and broadband absorption in the near-infrared and visible regions, and its solar power conversion efficiency of 13.8% is higher than the reported GaTe–InSe (9.1%), MoS2/p-Si (5.23%) and organic solar cells (11.7%). It does project PN-WSe2 heterostructure a potential for application in excitons-based solar cells.

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Evaluation of an enzyme immunoassay kit for estrogen receptor measurement--report II.

Clinical Chemistry ◽

10.1093/clinchem/34.10.2053 ◽

1988 ◽

Vol 34 (10) ◽

pp. 2053-2057 ◽

Cited By ~ 2

Author(s):

S Raam ◽

D M Vrabel

Keyword(s):

Enzyme Immunoassay ◽

Binding Sites ◽

Solid Phase ◽

Functional Characterization ◽

Quantitative Agreement ◽

Type I ◽

Type Ii ◽

Immunoreactive Protein ◽

Estrogen Binding

Abstract We present evidence to show that monoclonal antibodies to estrogen receptors (ER) in solid phase recognize the secondary estrogen binding sites with moderate to low affinity for estradiol (E2). An excellent quantitative agreement was found in five cytosols between the ER values obtained by the enzyme immunoassay (ER-EIA) and the amount of secondary estrogen binding sites measured by the assay involving dextran-coated charcoal (Clin Chem 1986;32:1496). The immunoreactive protein recognized by the antibody-coated beads, when allowed to react with ER(+) cytosols, is shown to bind [3H]estradiol only when the ligand concentration exceeds 8 nmol/L. Further biochemical and functional characterization of the immunoreactive protein is required to establish similarities/dissimilarities between this protein, high-affinity Type I ER sites, and the secondary sites such as Type II sites.

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Band Alignment Tailoring of InAs1−xSbx/GaAs Quantum Dots: Control of Type I to Type II Transition

Nano Letters ◽

10.1021/nl102237n ◽

2010 ◽

Vol 10 (8) ◽

pp. 3052-3056 ◽

Cited By ~ 25

Author(s):

J. He ◽

C. J. Reyner ◽

B. L. Liang ◽

K. Nunna ◽

D. L. Huffaker ◽

...

Keyword(s):

Quantum Dots ◽

Band Alignment ◽

Type I ◽

Type Ii

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Geochemical characterization of hydrocarbon source rocks of the Triassic-Jurassic time interval in the Mandawa basin, southern Tanzania: Implications for petroleum generation potential

South African Journal of Geology ◽

10.25131/sajg.123.0037 ◽

2020 ◽

Vol 123 (4) ◽

pp. 587-596

Author(s):

A. Emanuel ◽

C.H. Kasanzu ◽

M. Kagya

Keyword(s):

Source Rocks ◽

Geochemical Data ◽

Time Interval ◽

Type I ◽

Hydrocarbon Generation ◽

Type Ii ◽

Geochemical Characterization ◽

Type Iii ◽

Petroleum Generation

Abstract Triassic to mid-Jurassic core samples of the Mandawa basin, southern Tanzania (western coast of the Indian Ocean), were geochemically analyzed in order to constrain source rock potentials and petroleum generation prospects of different stratigraphic formations within the coastal basin complex. The samples were collected from the Mihambia, Mbuo and Nondwa Formations in the basin. Geochemical characterization of source rocks intersected in exploration wells drilled between 503 to 4042 m below surface yielded highly variable organic matter contents (TOC) rated between fair and very good potential source rocks (0.5 to 8.7 wt%; mean ca. 2.3 wt%). Based on bulk geochemical data obtained in this study, the Mandawa source rocks are mainly Type I, Type II, Type III, mixed Types II/III and Type IV kerogens, with a predominance of Type II, Type III and mixed Type II/III. Based on pyrolysis data (Tmax 417 to 473oC; PI = 0.02 to 0.47; highly variable HI = 13 to 1 000 mg/gTOC; OI = 16 to 225 mg/g; and VR values of between 0.24 to 0.95% Ro) we suggest that the Triassic Mbuo Formation and possibly the mid-Jurassic Mihambia Formation have a higher potential for hydrocarbon generation than the Nondwa Formation as they are relatively thermally mature.

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