People

Principle Investigator

 

Derby_2014 Jeffrey Derby

  Hometown: Richfield, MN  
  Undergraduate University: California Institute of Technology 
  Graduate University: Massachusetts Institute of Technology

 

 

 

 

Post-Doctoral Associates

 

Chung-Hsuan Huang

Undergraduate University: National Taiwan University, Taiwan

Graduate University: University of Minnesota

Research: I implement and develop finite-element models that describe particle engulfment during solidification and apply these models for subsequent analysis of these phenomena.

 

Graduate Students

 

Kerry Wang

Hometown: Plano, TX

Undergraduate University: Rice University

Research: Today, single-crystalline silicon solar cells are grown by the Czochralski method, a method that produces high-purity crystals but is very expensive.  Grown boules have to be sawed using a diamond-coated wiresaw, which produces cells of varying quality as the saw ages as well as loses nearly 40% of the material to sawdust (known as "kerf loss").  I am investigating the feasibility of a novel way of growing high-purity single-crystalline silicon for solar cell applications, a method known as Horizontal Ribbon Growth or HRG.  In HRG, a jet of inert gas blows over a shallow crucible of molten silicon, initiating a film of silicon that floats on the surface.  This film is continually pulled off, as the jet continually solidifies more film behind it. The HRG method seeks to drastically cut the cost of manufacturing high quality silicon solar cells.

 

Chang Zhang

Hometown: Hangzhou, Zhejiang, China

Undergraduate university: Zhejiang University, China

Hobbies: Hiking, traveling, running, movies, folk music, volunteering...

Research: I am modeling the thermal stress in the BaBrCl crystal during its growth process, which causes the cracking. I aim to understand the origin of the thermal stress and relieve it by finding optimal growth parameters and furnace design. The result of this research may allow us to grow large, crack free scintillator crystals.

 

Scott Dossa

Hometown: Eden Prairie, MN

Undergraduate University: Carleton College

Hobbies: Running, Climbing, Hiking, Watching Documentaries, and Playing Games

Research: One technique for discovering novel materials is Floating Zone Crystal Growth. Crystals grown by this method are often small, research-grade samples which are tested for special properties and characteristics. Growing crystals via floating zone is difficult even when the properties of the material are well understood. This is not the case for novel materials. I model crystals being grown inside floating zone furnaces in order to find out which experimental parameters make growth possible and determine parametric sensitivities of the system.

 

Linmin Wang

Hometown: Oakland, CA/Yueyang, Hunan, China

Undergraduate University: University of California, Santa Barbara

Hobbies: Reading (include but is not limited to, history of modern mathematics and physics (1700 to present), anecdotes of nearly all notable mathematicians and scientists, briefing articles on modern physics branches developed since 1930 and onwards, weaponries in World War II…), general relativity, computer technology trending, movies, home chemistry experiment (used to)

Research: Sapphire (Al2O3), owing to its strong mechanical strength, high transparency and high electrical insulation, has become increasingly important to our daily life and national defense, due to its potential applications as smart device touch screen faceplates, Radar windows on missiles, ideal substrate for growing efficient LED’s. However, industries dedicated to growing large high-quality sapphire boules have been plagued by the micron-sized bubbles, that are often found to be incorporated in the crystal during growth, thereby lowering the product quality and the yield. My research tackles this problem from two aspects, namely, 1) predict the concentrations of gas species present in the bubbles on the basis of both thermodynamics and kinetics, by minimization of Gibbs free energy of the system, to pinpoint possible reactions that generate gas phase product; 2) built a mathematical model accounting for fluid dynamics, mass transfer and heat transfer to fundamentally understand how bubbles are engulfed at the melt-solid interface and how to prevent their formation.

 

John Roerig

Hometown: Rush City, MN

Undergraduate university: Hamline University

Hobbies: Tinkering with computers (hardware and software), camping, solving puzzles.

 

Swanand Pawar

Hometown: Pune, India

Undergraduate University: Indian Institute of Technology, Guwahati

Hobbies: Sudoku

Research: Scintillator crystals play a key role in detection of nuclear radiation, and hence are important from the point of view of national security. As more new scintillator materials are being discovered, it is becoming very important to device techniques for growing good quality scintillator crystals. I work on designing a model-based control strategy for growth of these crystals. The objective of control in this case is to maintain optimal temperature and flow profiles in the crystal growth furnace and melt of the crystal for the entire duration of growth.