170520 Dark Matter, SuperCDMS Experiment, and the Super(conductive) Future of Particle Physics

Title:
Dark Matter, SuperCDMS Experiment, and the Super(conductive) Future of Particle Physics

Speaker:
Yen-Yung Chang (Caltech)

Time: 
05/20 (Sat.) 15:00 PDT, 16:00 MDT, 17:00 CDT, 18:00 EDT,
05/21 (Sun.) 06:00 Taiwan

Link:
Join the talk on BlueJeans: https://bluejeans.com/6366170552/

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Abstract:

This talk will focus on dark matter, the concept public media refers to more often as “Cosmos’ 10 (or 5) greatest mysteries [1],” or “the 26% (or 95% if they’ve got the idea wrong) of the Universe no one understands [2].” I will separate the talk into two seemingly unrelated parts: 1. Dark matter physics and experiments for direct detection and 2. cryogenic solid state physics and superconductive microwave technology. After the talk, we will poll on if you are convinced the two paths will merge. The content of this talk, hopefully also our poll data, will be published in summer, so I appreciate if you’d discuss with me before recording or distributing the material.

Keywords:
part 1:  dark matter, (nuclear/electronic) elastic scattering, SuperCDMS
part 2:  phonon, superconductivity, Kinetic Inductance Detector (KID)

Prerequisite knowledge:

undergraduate physical science/engineering background
read the Wiki introduction of one of the keywords you are interested in

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[1] e.g. Dark Matter, Darker Still: The Cosmos' Greatest Mystery Deepens, TIME, Oct. 26^th, 2011
[2] e.g. The Dark Side of the Universe, The Guardian,  Mar. 2^nd, 2016

170506 Defect engineering and admittance spectroscopy study of CZTSSe solar cells

Title:
Defect engineering and admittance spectroscopy study of CZTSSe solar cells

Speaker:
Yi-Rung Lin (Visiting Postdoc in Caltech)

Time:
05/06 (Sat.) 15:00 PDT, 16:00 MDT, 17:00 CDT, 18:00 EDT,
05/07 (Sun.) 06:00 Taiwan

Link: 

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Join the talk on BlueJeans: https://bluejeans.com/6366170552/
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Abstract:
In the past decades, numerous promising solar cell concepts, ranging from single-crystallized silicon to thin-film based technologies, have been developed and are being studied intensely by an increasing number of scientific groups and companies. Within the thin-film based photovoltaic technology, kesterite-based Cu₂ZnSn(S,Se)₄ (CZTS) photovoltaics, which is the analogous of Cu(In,Ga)(S,Se)₂ (CIGS) photovoltaics, has emerged as a potential candidate absorber material for the next generation thin film solar cells due to their advantages of earth-abundance and low-cost requirements. In spite of the latest demonstration of solution-processed CZTS devices with over 12% power conversion efficiency, the development of CZTS as an absorber material is still behind in terms of both fundamental understanding of the material system and in the capability to precisely control the formation of MoSe₂ layer underneath of the absorber CZTS and Mo substrate for high-efficiency CZTS device, as compared with those of CIGS and CdTe. In this talk, I will present three key areas in this field to enhance the device performances, which include (1) Defect characterization and its relationship to carrier dynamics; (2) Modification of the interface of CZTS/Mo and (3) Solution-processing with environmentally friendly solvents for large-scale production.