Single crystal and polycrystalline copper indium selenide deposited by the hybrid sputtering and evaporation method for photovoltaic devices
Yang, Li-Chung
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/19418
Description
Title
Single crystal and polycrystalline copper indium selenide deposited by the hybrid sputtering and evaporation method for photovoltaic devices
Author(s)
Yang, Li-Chung
Issue Date
1994
Doctoral Committee Chair(s)
Rockett, Angus A.
Department of Study
Materials Science and Engineering
Discipline
Materials Science and Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Electronics and Electrical
Engineering, Materials Science
Language
eng
Abstract
The results presented here impact the CuInSe$\sb2$ solar cells community in three areas: (1) fundamental understanding of CuInSe$\sb2$ growth and properties, (2) development and optimization of a potentially scalable deposition technique, and (3) improvement in solar cell performance based on a novel adhesion-promoting back contact layer. Each of these impacts on the general problem of irreproducibility in production of high-performance CuInSe$\sb2$ solar cells.
The work presented in this thesis has shown that second phase separation is more rapid and film uniformity is greater at high deposition temperatures than at low temperatures in polycrystalline layers deposited by physical vapor deposition processes. Furthermore, the preferred orientation of common polycrystalline CuInSe$\sb2$ has been shown to result from minimization of the surface free energy rather than the substrate orientation. The combined results indicate that air heat treatment which is critical to optimized performance in most physical-vapor-deposited CuInSe$\sb2$ is probably due to passivation of high energy surfaces. The resistivity data collected from single crystals explains the preference for In-rich CuInSe$\sb2$ for devices and the implications of segregated layers at grain boundaries on device performances.
The composition of device layers not only affects their performance directly, but also was found in the process being used in this thesis to affect performance indirectly through adhesion failures. A novel contact design was demonstrated, including a unique metastable-phase precipitation, for improved adhesion. The rate limited supply of Cu precipitating from the substrate, dissolves in the CuInSe$\sb2$ layer modifying the chemistry at the back of the CuInSe$\sb2$ and improving the adhesion.
The integrated understanding resulting from the results presented here allowed the deposition process, back contact, and device fabrication to be optimized. This resulted in a 3% increase in the best performance and dramatic improvement in performance uniformity of solar cells incorporating on CuInSe$\sb2$ produced by the hybrid process.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
