Applications of Liquid Phase Epitaxy in Optoelectronic Devices
General Material Designation
[Thesis]
First Statement of Responsibility
Xin Zhao
Subsequent Statement of Responsibility
Woodall, Jerry M.
.PUBLICATION, DISTRIBUTION, ETC
Name of Publisher, Distributor, etc.
University of California, Davis
Date of Publication, Distribution, etc.
2016
PHYSICAL DESCRIPTION
Specific Material Designation and Extent of Item
89
GENERAL NOTES
Text of Note
Committee members: Hihath, Joshua; Islam, M. Saif
NOTES PERTAINING TO PUBLICATION, DISTRIBUTION, ETC.
Text of Note
Place of publication: United States, Ann Arbor; ISBN=978-1-369-20229-8
DISSERTATION (THESIS) NOTE
Dissertation or thesis details and type of degree
Ph.D.
Discipline of degree
Electrical and Computer Engineering
Body granting the degree
University of California, Davis
Text preceding or following the note
2016
SUMMARY OR ABSTRACT
Text of Note
Liquid phase epitaxy is a technique to grow high purity semiconductor crystals from a melt. This work explored applications of liquid phase epitaxy in two optical devices - solar cells and light emitting diodes. For the solar cell application, liquid phase epitaxy was used to optimize the efficiency of Al0.2Ga0.8As solar cells. Al0.2Ga 0.8As is the preferred material for the top sub-cell of a dual-junction solar cell based on an efficient crystalline silicon bottom sub-cell. Preliminary studies of Al0.2Ga0.8As epilayers grown by liquid phase epitaxy, including photo-luminescent and Hall effect studies, indicated that the material was of high quality in terms of both carrier lifetimes and mobility. Then three approaches of growing AlGaAs solar cells on GaAs substrates were experimented, among which an approach was identified as being suitable for producing efficient AlGaAs solar cells. The approach involves growing an n-type AlGaAs base first, followed by an isothermal Zn diffusion process to form the p-type AlGaAs emitter and the window layer. The approach also requires that the substrate be always protected by a thin layer of residual melt throughout the growth to prevent interface or surface oxidation, and that the window layer be subsequently removed by buffer oxide etch solution. An open-circuit voltage of 1.15 V and an efficiency of 6.56% was observed from our cell without anti-reflective coatings. For the light emitting diode application, liquid phase epitaxy was used to grow lattice-mismatched GaInP epilayers on GaP substrates. Layered growth of GaxIn1-xP on GaP was achieved when the lattice mismatch exceeds 0.4% (x<0.95) using a Sn-based melt. Compositional control was observed by (1) changing the cooling rate and (2) varying the melt-back temperature at the beginning of the growth.
TOPICAL NAME USED AS SUBJECT
Electrical engineering
UNCONTROLLED SUBJECT TERMS
Subject Term
Applied sciences;AlGaAs solar cells;Liquid phase epitaxy;Optoelectronic devices