scholarly journals Efficient Photocatalytic Hydrogen Evolution via Band Alignment Tailoring: Controllable Transition from Type-I to Type-II

Small ◽  
2017 ◽  
Vol 13 (41) ◽  
pp. 1702163 ◽  
Author(s):  
Zhongzhou Cheng ◽  
Fengmei Wang ◽  
Tofik Ahmed Shifa ◽  
Chao Jiang ◽  
Quanlin Liu ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Band Alignment ◽  
Type I ◽  
Type Ii ◽  
Photocatalytic Hydrogen Evolution

scholarly journals Ultrafast Charge Separation in Bilayer WS2/Graphene Heterostructure Revealed by Time- and Angle-Resolved Photoemission Spectroscopy

2021 ◽  
Vol 9 ◽  
Author(s):  
Razvan Krause ◽  
Mariana Chávez-Cervantes ◽  
Sven Aeschlimann ◽  
Stiven Forti ◽  
Filippo Fabbri ◽  
...  
Keyword(s):  
Charge Separation ◽  
Graphene Layer ◽  
Optoelectronic Devices ◽  
Visible Spectral Range ◽  
Band Alignment ◽  
Photoemission Spectroscopy ◽  
Type I ◽  
Type Ii ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Indirect Band Gap

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.

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

1997 ◽  
Vol 79 (2) ◽  
pp. 269-272 ◽  
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

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

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.

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

Nano Letters ◽  
2010 ◽  
Vol 10 (8) ◽  
pp. 3052-3056 ◽  
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

Type I–type II band alignment of a GaAsSb/InAs/GaAs quantum dot heterostructure influenced by dot size and strain-reducing layer composition

2013 ◽  
Vol 46 (9) ◽  
pp. 095103 ◽  
Author(s):  
A Hospodková ◽  
M Zíková ◽  
J Pangrác ◽  
J Oswald ◽  
J Kubištová ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Band Alignment ◽  
Type I ◽  
Type Ii ◽  
Gaas Quantum Dot ◽  
Layer Composition

Electrical Properties of n-GaN/p-SiC and n-AlGaN/p-SiC Heterojunction Diodes

2001 ◽  
Vol 693 ◽  
Author(s):  
B. Luo ◽  
J. Kim ◽  
R. Mehandru ◽  
F. Ren ◽  
K. P. Lee ◽  
...  
Keyword(s):  
Activation Energy ◽  
Band Alignment ◽  
Type I ◽  
Type Ii ◽  
Normal Type ◽  
Defect States ◽  
Dark Line ◽  
Continuous States ◽  
Line Defects ◽  
Heterojunction Diodes

AbstractProperties of n-GaN/p-SiC and n-AlGaN/p-SiC heterojunctions prepared by HVPE on 4H SiC substrates were studied by means of C-V, C/G-T, C-f, I-V and DLTS. It is shown, in agreement with earlier publications, that the GaN/p-SiC HJ is staggered type II with ΔEc=-0.4 eV andΔEv=0.6 eV. Whenchanging GaN for AlGaN with Al mole fraction of x=0.25-0.3 the band alignment becomes normal type I with ΔEc=0.2 eV andΔEv=0.6 eV. I-V characteristics of both heterojunctions bear evidence of strong tunneling via defect states, particularly centers with activation energy of 1.25 eV for GaN/4H SiC HJ. The tunneling was found to be more pronounced in the AlGaN/SiC HJs even though these HJs showed no evidence of formation of dark line defects at the interface, in contrast to GaN/SiC. DLTS measurements on both types of HJs revealed the presence of broad bands whose behavior is indicative of these bands being related to continuous states in the gap, most likely near the nitride/carbide interface.

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