A Caltech Library Service

Spontaneous Pattern Formation in Photoelectrodeposited Semiconductor Films


Batara, Nicolas Anthony (2017) Spontaneous Pattern Formation in Photoelectrodeposited Semiconductor Films. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z98S4MZ4.


The ability to manipulate matter with ever-increasing precision has enabled the fabrication of nanoscale structures with unprecedented utility. Scalable patterning technologies have dramatically transformed diverse application spaces such as computing and photonics, in part due to diminishing cost per unit area. The work in this thesis presents a template-free, bottom-up technique based on photoelectrodeposition which allows the direct fabrication of periodically nanostructured thin films of semiconductor material over large areas.

First, we examine the effects of wavelength, polarization and incidence angle of illumination on the film morphology. We develop an understanding of the pattern formation to be the result of interference of light scattered across the surface of the growing interface. We also examine the morphological effects of more complex illumination conditions. For example, when deposited under two different illumination wavelengths, the period of patterned films self-optimizes to concentrate light absorption to the tips of the nanostructures . Additionally, we find that the relative polarization angles and phases of two illumination sources can be tuned to produce film morphologies ranging from isotropic mesh-type patterns to orthogonally arranged, intersecting lamellar structures with independent periodicities.

We deepen our understanding of these observations by building a probabilistic computational model that correlates the local light absorption with a local growth probability at the interface of the film with few material parameters. We find that this model is able to reproduce experimentally observed morphological features for all illumination conditions investigated in this work. Through Fourier analysis, we find quantitative agreement between the simulated and experimental periods. Separately, we use electrodynamic simulations on idealized lamellar structures to understand the effect of two coincident illumination sources on the spatial absorption profile.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:nanotechnology; semiconductors; chalcogenide; photoelectrodeposition; electrodeposition; self-assembly; nanophotonics
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Materials Science
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Atwater, Harry Albert (co-advisor)
  • Lewis, Nathan Saul (co-advisor)
Thesis Committee:
  • Atwater, Harry Albert (chair)
  • Lewis, Nathan Saul
  • Greer, Julia R.
  • Bernardi, Marco
Defense Date:24 October 2016
Non-Caltech Author Email:nick.batara (AT)
Funding AgencyGrant Number
U.S. Department of Energy, Office of Science, Office of Basic Energy SciencesDE-SC0001293
Record Number:CaltechTHESIS:06032017-161239736
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for Ch. 2 adapted for Ch. 3 adapted for Ch. 4 adapted for Ch. 5
Batara, Nicolas Anthony0000-0002-9154-4577
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10262
Deposited By: Nicolas Batara
Deposited On:07 Jun 2017 17:24
Last Modified:08 Nov 2023 00:12

Thesis Files

PDF - Final Version
See Usage Policy.


Repository Staff Only: item control page