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You searched for +publisher:"University of Illinois – Chicago" +contributor:("Berry, Vikas"). Showing records 1 – 3 of 3 total matches.

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University of Illinois – Chicago

1. Yu, Xin. Transfer-Free Development of Graphene-on-Silicon Heterojunction Solar Cells.

Degree: 2017, University of Illinois – Chicago

Two-dimensional nanomaterials (2DNs) due to their broadband absorption (graphene) and high absorption coefficient (MoS2 or WS2) are attractive for optoelectronics including solar cells. Recent advances in 2DNs-based photovoltaics is based on interfacing 2DNs with conventional bulk 3D semiconductors to build a new class of 2D/3D heterojunction solar cells. Currently, such 2D/3D heterojunction solar cell devices are fabricated via mechanical/chemical transfer of 2D layers onto 3D bulk semiconductors, which poses challenges for large-scale integrations. In this project, transfer-free, large-area graphene/n-silicon (G/n-Si) heterojunction solar cells are developed via chemical vapor deposition (CVD). The directly-grown graphene films are characterized via combined spectroscopic (Raman and XPS) and microscopic (FESEM) techniques. Several CVD process optimizations have been made to understand the growth kinetics of graphene on n-Si surfaces. A power conversion efficiency of 1.3% is achieved for G/n-Si heterojunction solar cells with silver nanoparticles as plasmonics centers. Factors such as: structural quality, quantum opto-plasmonics affecting the performances of these new generation photovoltaics will be discussed. Advisors/Committee Members: Berry, Vikas (advisor).

Subjects/Keywords: Graphene; Silicon; Solar Cell; Heterojunction

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APA (6th Edition):

Yu, X. (2017). Transfer-Free Development of Graphene-on-Silicon Heterojunction Solar Cells. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/21749

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Yu, Xin. “Transfer-Free Development of Graphene-on-Silicon Heterojunction Solar Cells.” 2017. Thesis, University of Illinois – Chicago. Accessed August 24, 2019. http://hdl.handle.net/10027/21749.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Yu, Xin. “Transfer-Free Development of Graphene-on-Silicon Heterojunction Solar Cells.” 2017. Web. 24 Aug 2019.

Vancouver:

Yu X. Transfer-Free Development of Graphene-on-Silicon Heterojunction Solar Cells. [Internet] [Thesis]. University of Illinois – Chicago; 2017. [cited 2019 Aug 24]. Available from: http://hdl.handle.net/10027/21749.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Yu X. Transfer-Free Development of Graphene-on-Silicon Heterojunction Solar Cells. [Thesis]. University of Illinois – Chicago; 2017. Available from: http://hdl.handle.net/10027/21749

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


University of Illinois – Chicago

2. Deng, Shikai. Structure Design and Properties Modification Based on Wrinkling of Two-Dimensional Nanomaterials.

Degree: 2017, University of Illinois – Chicago

Structure and strain engineering is the process of tuning a material's properties by altering its mechanical or structural attributes. Atomically thin two-dimensional nanomaterials (2DNMs), such as graphene, boron nitride, and transition metal dichalcogenides (MoS2, WS2, etc.), which have been extensively studied in recent years, are particularly well-suited for strain engineering because they can withstand large strains. Wrinkling has shown its great advantages to introduce well-controlled local structure and strain in 2DNMs. However, the studies on understanding of the wrinkles formation, wrinkling processes for nanoscale confined and directed wrinkles, and wrinkle-effect and application in 2DNMs are still in its infancy. This thesis first shows that parallel and self-similar hierarchical wrinkles pattern can be formed on ultrathin cobalt/chromium film atop a contracting silicone oil meniscus. Interesting, these wrinkle attributes do not follow the standard von-Kármán wrinkling scaling near the edge, attributed to the added surface energy (L/λ ∝ (A/t)0.31). An energy model is developed and shows a linear relation between the amplitude and the length of wrinkles at all observed hierarchic levels (L ∝ A). Additionally, wrinkles (wavelength = 10 nm ∼ 10 μm) can be found in mechanical exfoliated MoS2 flakes on silicon-based substrates (SiO2 and Si3N4). A mechanical energy model is proposed that equates the adhesion energy of MoS2 on SiO2 and Si3N4 to the attributes of a single wrinkle in a MoS2 flake. The adhesion energy values of 0.170 ± 0.033 J m–2 for MoS2 on SiO2 and 0.252 ± 0.041 J m–2 for MoS2 on Si3N4 are determined. Further, we show that selective desiccation of a bacterium under impermeable and flexible graphene via a flap-valve operation produces axially aligned graphene wrinkles of wavelength 32.4–34.3 nm, consistent with modified Föppl–von Kármán mechanics (confinement ∼0.7 × 4 μm2). An electrophoretically oriented bacterial device with confined wrinkles aligned with van der Pauw electrodes is fabricated and exhibited an anisotropic barrier (ΔE = 1.69 meV). Finally, we show that wrinkles can induce uniaxial strain, spatially reconfigured doping distribution, phonon softening (2 cm-1/% deformation for Raman E12g mode), and reduction of the optical bandgap (40∼60 meV/% deformation) in multilayer MoS2 flakes. A larger barrier (ΔEA= 106.6 meV) and a higher carrier mobility are exhibited in the MoS2 devices with wrinkles in the field-effect transistor studies. Further, a 1000-fold improvement in the on/off ratio and a 10-fold photocurrent enhancement over flat MoS2 devices are also observed in optoelectronic studies. This phenomenon is attributed to the exciton funneling and the built-in potential induced by bandgap-reduction and doping-variation in wrinkled devices. Advisors/Committee Members: Berry, Vikas (advisor).

Subjects/Keywords: Two-dimensional nanomaterials; wrinkles; strain engineering; nanostructure

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Deng, S. (2017). Structure Design and Properties Modification Based on Wrinkling of Two-Dimensional Nanomaterials. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/22248

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Deng, Shikai. “Structure Design and Properties Modification Based on Wrinkling of Two-Dimensional Nanomaterials.” 2017. Thesis, University of Illinois – Chicago. Accessed August 24, 2019. http://hdl.handle.net/10027/22248.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Deng, Shikai. “Structure Design and Properties Modification Based on Wrinkling of Two-Dimensional Nanomaterials.” 2017. Web. 24 Aug 2019.

Vancouver:

Deng S. Structure Design and Properties Modification Based on Wrinkling of Two-Dimensional Nanomaterials. [Internet] [Thesis]. University of Illinois – Chicago; 2017. [cited 2019 Aug 24]. Available from: http://hdl.handle.net/10027/22248.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Deng S. Structure Design and Properties Modification Based on Wrinkling of Two-Dimensional Nanomaterials. [Thesis]. University of Illinois – Chicago; 2017. Available from: http://hdl.handle.net/10027/22248

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


University of Illinois – Chicago

3. Khan, Sameera. Engineered Surfaces for Dew Harvesting.

Degree: 2017, University of Illinois – Chicago

Structured surfaces have drawn considerable attention from both theoretical and experimental points of view due to their potential in enhancing the heat transfer coefficient by achieving desirable wetting properties, in many industrial applications such as thermal storage, water harvesting and power generations. Considering the water scarcity as one of the most challenging issue nowadays, here we apply a new technique for water harvesting through condensation phenomenon. This technique has the advantage of a) typically the source of the water for harvesting is external and comes from the nature such as sea or rain, but here a vapor stimulation process is applied to capture the vapors which have the potential to provide water by phase change process-condensation. b) using remarkable less input energy compared to the typical techniques of water harvesting. In the above mentioned application (water-harvesting), fast formation and subsequent removal of water droplets is critical for enhancing the efficiencies of their associated systems. Significant focus has been placed on the aspect of droplet removal from the surfaces, that has led to development of superhydrophobic surfaces with special textures on which droplets are self-removed after coalescence. Due to their inherent low surface energy, nucleation energy barrier is also high. In contrast to conventional superhydrophobic surfaces, here we show the surfaces can be engineered such that the simultaneous benefits of high nucleation rates and fast droplet removal can be obtained during the condensation process. The main objective of this work is to develop a fundamental understanding of impregnated oils in textured surfaces from theoretical and from experimental point of view, for enhanced condensation further leading to the application of dew harvesting. Advisors/Committee Members: Berry, Vikas (advisor), Anand, Sushant (advisor).

Subjects/Keywords: Dew Harvesting; LIS; Fabrication; Nano micro textures; water collection; photolithography; etching; nucleation

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Khan, S. (2017). Engineered Surfaces for Dew Harvesting. (Thesis). University of Illinois – Chicago. Retrieved from http://hdl.handle.net/10027/22243

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Khan, Sameera. “Engineered Surfaces for Dew Harvesting.” 2017. Thesis, University of Illinois – Chicago. Accessed August 24, 2019. http://hdl.handle.net/10027/22243.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Khan, Sameera. “Engineered Surfaces for Dew Harvesting.” 2017. Web. 24 Aug 2019.

Vancouver:

Khan S. Engineered Surfaces for Dew Harvesting. [Internet] [Thesis]. University of Illinois – Chicago; 2017. [cited 2019 Aug 24]. Available from: http://hdl.handle.net/10027/22243.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Khan S. Engineered Surfaces for Dew Harvesting. [Thesis]. University of Illinois – Chicago; 2017. Available from: http://hdl.handle.net/10027/22243

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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