Allen J. Hall

Materials Science & Engineering, Productivity, and Life

I have 10+ years of research experience in two major areas of materials science and engineering. Among numerous other small projects and duties at the University of Illinois at Urbana-Champaign, I have worked on the following.

AFM showing two grains of copper indium diselenide.

AFM showing two grains of copper indium diselenide.

In the field of semiconductors, in specific photovoltaics:

  • • In order to solve the difficulties in studying the grain boundaries in CuInSe2, I proposed a new method of grain-boundary study: the idea of studying of a single well understood grain-boundary purposefully grown into epitaxial thin films of CuIn(Ga)Se2. The program has been broadened to two graduate students and an international collaboration with Hans Meitner Institute, funded by a National Science Foundation grant.
  • • During this work, I’ve also helped to implement and develop various techniques in the Materials Research Laboratory for studying photovoltaics. In particular, I implemented LBIC/OBIC measurements in the Alpha-SNOM in the laser facilities in MRL.
  • • I have also designed and implemented a radio-frequency ionized plasma physical vapor deposition assist system (i-PVD) and implemented it in our growth chamber, among numerous part designs and repairs for the growth system.
X-ray Reciprocal Space Map showing unit-cell expansion possibly due to gallium diffusion along the (100) direction

X-ray Reciprocal Space Map showing unit-cell expansion possibly due to gallium diffusion along the (100) direction

In the field of Polymer Science and Engineering:

  • • I synthesized a new low-cost medium temperature polyester thermosetting resin based upon glyptal resins.
  • • I studied interchain transesterification reactions (ITR) in both thermosets and thermoplastics using lap-shear measurements and compression molding of structural composites.
  • • I created novel nanoparticulates of all aromatic thermoset polyesters using interfacial solution polymerization using ultrasound techniques.

To get a more detailed list of the things I’ve done, please feel free to contact me for my Resume and check out my Linked In page.

If you would like to contact me in regards to consulting, please feel free to use my PGP/GPG public key to ensure our discussions will remain private.

My New Nanostructured CI(G)S Light-Absorbing Thin Films Published in JAP

pillars For a while now I’ve been dying to share some of the new nanostructures I’ve discovered during ion-assisted vapor deposition of CI(G)S thin films. My paper was published in the Journal of Applied Physics last fall (sorry for the blog outage over the winter-break).  The paper is titled: “Nanostructured light-absorbing crystalline CuIn(1–x)GaxSe2 thin films grown through high flux, low energy ion irradiation;”  There are a lot of unanswered questions about the work that leaves me dreaming up different solutions to how these films are growing. Read More »

Simple Matlab Gui Programs for Crystal Symmetry Calculations

Tetragonal Symmetry Angle GuiI’ve made a few small gui programs (MATLAB) for finding all unique angles for vectors (or plane normals) in both the cubic and tetragonal crystal spaces. I thought I’d share them here, as I finally worked out a few kinks. Be aware that the little gui’s use the command window to output their results. Some of my other programs would output latex code so that they could be pasted directly into a thesis for tables etc., but this one just uses the standard out (ala the command window in Matlab).

Essentially you enter the vectors for the two planes of interest, then hit calculate, and all the unique angle solutions for the crystal space you chose (one gui for each crystal space right now- no interest in complicating it by combining at this time) gets output in the command window.

I populate some orientation matrices based upon the vectors you give. Then, from matrix calculations, using tetragonal and crystal symmetry operations, we determine all the symmetric orientations. Then, a simple subspace() command gives us the angles of greatest rise (dihedral angle) between the symmetric orientations. The calculations for these operations can be found in my Thesis (if it ever gets published), but can also be found in: V. Randle and O. Engler. Texture Analysis: Macrotexture, Microtexture & Orientation Mapping. CRC Press, 2000.

Please note- it’s your job to check if these are correct, I make no warranties about this stuff. :) It should work, but feel free to go in and edit everything to your liking. If you use my code, don’t worry too much about citing me (if you do, I appreciate it, but I often leave out others who have contributed also).

These are very simple, but hopefully they’ll help a bit for those working in cubic and tetragonal spaces.

Here’s the cubic symmetry angle calculator:
Vector Angle Calculator Cubic Symmetries

Here’s the tetragonal symmetry angle calculator:
Vector Angle Calculator Tetragonal Symmetries

I hope they work for you- please let me know if you have problems, if I have time I’ll try and help.

Finally- Qspace mapping success!

I have no idea why this took so long, but I finally have the code to import and output various graphs of the reciprocal space maps (RLM or Q-space) taken using the Xpert Xray diffraction system. One of the difficulties in outputting the older data has been solved by our new line-scan detector system. The data is now taken in the more simple Omega-2Theta space instead of Omega-Omega2Theta space. With the help of Mauro Sardela, the fantastic research scientist who runs the XRD lab at the Materials Research Laboratory (FS-MRL), I’ve properly translated the data into Q-space using the same equations the Xpert Epitaxy software uses.
Read More »

A Quick Introduction...

I'm a graduate student (PhD Candidate) at the University of Illinois at Urbana-Champaign.

I've studied and researched in two fields of Materials Science and Engineering (Polymers and Semiconductors). My interests are as diverse as my musical tastes and I usually have my hand in some crazy project during my free time.

I'm available for consulting and have access to a world-renown materials research user-facility supported by the D.O.E. If you would like to know more, please contact me.

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