Liquid phase electroepitaxial bulk growth of binary and ternary alloy semiconductors under external magnetic field
Date
2018-11-09
Authors
Sheibani, Hamdi
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Abstract
Semiconducting single crystals are vital to the electronics industry. A number of methods
have been developed to produce or ’’grow” these materials. A widely used group of growth
techniques is known as the growth from solution. In these methods layers of single crystals
are grown at relatively low temperatures. Liquid Phase Electroepitaxy (LPEE) falls in this
category, and is a relatively new, promising technique for producing high quality, thick
compound semiconductors and their alloys.
The availability of thick alloy substrates will solve problems arising from lattice mismatch
encountered in the integration of different material layers, and will open new horizons
in the fabrication technology of opto-electronic devices and integrated circuits . The
growth of GnAs and InGaAs crystals is an ideal vehicle for the development of a ternary
crystal growth process.
Various features of LPEE as well as a low cost of hardware make this technique quite
attractive for the growth of high quality alloy semiconductors in the form of both bulk
crystals and buffer layers. However, reproducible growth of such crystals depends on the
understanding and control of the key mechanisms governing the LPEE growth process.
Among these factors, both the gravity induced natural convection in the solution and Joule
heating in the growth cell are of the utmost importance. They have adverse effects on the
quality of grown crystals and the stability of the growth interface.
The main objectives are to reduce the adverse effect of natural convection and to determine
the optimum growth conditions for reproducible desired crystals for the optoelectronic
and electronic device industry. Among the available techniques for suppressing the
adverse effect of natural convection, the application of an external magnetic field seems the
most feasible one.
The research work in this dissertation consists of two parts. The first part is focused on
the design and development of a state of the art LPEE facility with a novel crucible design,
that can produce bulk crystals of quality higher than those achieved by the existing LPEE
system. A growth procedure was developed to take advantage of this novel crucible design.
The research of the growth of InGaAs single crystals presented in this thesis will be a
basis for the future LPEE growth of other important material and is an ideal vehicle for the
development of a ternary crystal growth process.
The second part of the research program is the experimental study of the LPEE growth
process of high quality bulk single crystals of binary/ternary semiconductors under applied
magnetic field. The compositional uniformity of grown crystals was measured by Electron
Probe Micro-analysis (EPMA) and X-ray microanalysis.
The state-of-the-art LPEE system developed at University of Victoria, because of its
novel design features, has achieved a growth rate of about 4.5 mm/day (with the application
of an external fixed magnetic field of 4.5 KGauss and 3 A/cm2 electric current density), and
a growth rate of about 11 mm/day (with 4.5 KGauss magnetic field and 7 A/cm2 electric
current density). This achievement is simply a breakthrough in LPEE, making this growth
technique absolutely a bulk growth technique and putting it in competition with other bulk
growth techniques. The growth rates achieved can even be higher for higher electric current
and magnetic field intensities.
Description
Keywords
Semiconductors, Ternary alloy, Liquid-phase electroepitaxy, Electroepitaxial