A Comparative Study on Optical Characteristics of InGaAsP QW Heterostructures of Type-I and Type-II Band Alignments

In this paper, we have configured InGaAsP QW (quantum well) heterostructures of type-I and type-II band alignments and simulated their optical characteristics by solving 6 x 6 Kohn-Luttinger Hamiltonian Matrix. According to the simulation results, the InGaAsP QW heterostructure of type-I band alignment has been found to show peak optical gain (TE mode) of the order of~3600/cm at the transition wavelength~1.40 µm; while of type-II band alignment has achieved the peak gain (TE mode) of the order of~7800/cm at the wavelength of~1.85 µm (eye safe region). Thus, both of the heterostructures can be utilized in designing of opto-or photonic devices for the emission of radiations in NIR (near infrared region) but form the high gain point of view, the InGaAsP of type-II band alignment can be more preferred.

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Broadband Detection Based on 2D Bi2Se3/ZnO Nanowire Heterojunction

Crystals ◽

10.3390/cryst11020169 ◽

2021 ◽

Vol 11 (2) ◽

pp. 169

Author(s):

Zhi Zeng ◽

Dongbo Wang ◽

Jinzhong Wang ◽

Shujie Jiao ◽

Donghao Liu ◽

...

Keyword(s):

Zinc Oxide ◽

Surface State ◽

Near Infrared ◽

Infrared Region ◽

Band Alignment ◽

Type I ◽

Zno Nanowire ◽

Heterojunction Device ◽

Near Infrared Region ◽

Broadband Detection

The investigation of photodetectors with broadband response and high responsivity is essential. Zinc Oxide (ZnO) nanowire has the potential of application in photodetectors, owing to the great optoelectrical property and good stability in the atmosphere. However, due to a large number of nonradiative centers at interface and the capture of surface state electrons, the photocurrent of ZnO based photodetectors is still low. In this work, 2D Bi2Se3/ZnO NWAs heterojunction with type-I band alignment is established. This heterojunction device shows not only an enhanced photoresponsivity of 0.15 A/W at 377 nm three times of the bare ZnO nanowire (0.046 A/W), but also a broadband photoresponse from UV to near infrared region has been achieved. These results indicate that the Bi2Se3/ZnO NWAs type-I heterojunction is an ideal photodetector in broadband detection.

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Photoluminescence of multi-layer GeSi dots grown on Si (001)

MRS Proceedings ◽

10.1557/proc-667-g6.4 ◽

2001 ◽

Vol 667 ◽

Author(s):

J. Wan ◽

Y. H. Luo ◽

G. L. Jin ◽

Z. M. Jiang ◽

J. L. Liu ◽

...

Keyword(s):

Molecular Beam ◽

Layer Structure ◽

Peak Position ◽

Band Alignment ◽

Type I ◽

Type Ii ◽

Wetting Layer ◽

Gas Source ◽

Band Alignments ◽

Wetting Layers

ABSTRACTTemperature and power dependent photoluminescence measurements were carried out on the multi-layer structure of GeSi dots grown on Si(001) substrate by gas-source molecular beam epitaxy. The transfer of photon-induced carriers from wetting layers into the dots and the region near the dots was evidenced. Different power dependent behaviors of the photoluminescence peak position were observed for the dots and the wetting layer. Accordingly, type-II and type-I band alignments were proposed for the dots and the wetting layers, respectively. After annealing, the photoluminescence peaks from the dots and the wetting layers showed blueshift due to the atomic intermixing. For the samples annealed at temperature above 850°C for 5min, the band alignment of the dots changes from type-II to type-I.

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

Small ◽

10.1002/smll.201702163 ◽

2017 ◽

Vol 13 (41) ◽

pp. 1702163 ◽

Cited By ~ 23

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

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

Frontiers in Physics ◽

10.3389/fphy.2021.668149 ◽

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.

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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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