We describe the growth and characteristics of GaN based light emitting diodes grown on Si(111) substrates. We show that the UV electroluminescence of such diodes can be used to generate fluorescence in organic color converters so that multicolored hybrid nitride-organic light emitting diodes that emit in the visible can be prepared.
We report the use of photoluminescence imaging as a quick and effective method for determining defect densities and giving insight into degradation mechanisms in II-VI CdxZn1-xSe quantum well devices and heterostructures grown on GaAs. From our use of photoluminescence imaging we have observed that the device lifetimes are dependent on the stacking fault density. The stacking faults serve as nonradiative recombination centers that generate the dark line defects. In our studies, degradation rates were found to be independent of chlorine doping, barrier material, and the removal of the GaAs substrate.
We present results for lattice matched (AlxGai..xAs, x=0.5 and x=0.0) and lattice mismatched
(InxGai..xAs, x□0.25) growth on patterned GaAs (100) substrates. For the AlGai..xAs structures, the
GaAs substrates were patterned in the form of elongated mesas parallel to [011 II with widths of
approximately 3 tim. Interfacet migration effects observed on the nesas via cross-section transmission
electron microscope studies are explained in terms of a ledge-ledge interaction on the vicinal surfaces
formed due to growth on the mesas. InxGai..xAs (x□0.25) structures were grown on GaAs (100)
substrates patterned in the form of elongated mesas parallel to [01 11 with widths of approximately 1 tim.
This patterning direction was chosen since under cutting in the [0 1 1] direction eliminates inter-facet
migration effects so that compositional change induced strain effects can be minimised. For x □0.15, we
find a reduction in misfit dislocation densities in films upto five times the nominal critical thickness for
growths on the patterned mesas as compared to the growths on the corresponding non patterned regions.
For x=0.25 no such difference is observed and a large number ofthreading dislocations ( around iO cm2)
are found in both the patterned and the non patterned regions. This is believed to be a consequence of the
onset ofa 3-D island growth mode. Finally we present some results for the growth of InØ5Gaj•75As I
AlAs resonant tunneling diode (RTD) structures and a 100 period InjØGaØ8As (80 A) IGaAs (160 A)
Multiple Quantum Well (MQW) such as suited for spatial light modulator (SLM) structures on GaAs (100)
substrates patterned in both <01 1> directions on a length scale of 12 to 20 tm. For the RTD structures we
conclude that benefits from patterning are expected for x□0.25 provided the growth kinetics are
appropriately adjusted to prevent 3D island growth mode. For the MQW -SLMstructure we demonstrate
superior optical properties for the growth in the patterned region and a corresponding absence of threading
dislocations in the central region of the mesas.
Conference Committee Involvement (11)
Low-Dimensional Materials and Devices 2018
22 August 2018 | San Diego, California, United States
Low-Dimensional Materials and Devices 2017
9 August 2017 | San Diego, California, United States
Low-Dimensional Materials and Devices 2016
30 August 2016 | San Diego, California, United States
Low-Dimensional Materials and Devices
12 August 2015 | San Diego, California, United States
Nanoepitaxy: Materials and Devices VI
19 August 2014 | San Diego, California, United States
Nanoepitaxy: Materials and Devices V
25 August 2013 | San Diego, California, United States
Nanoepitaxy: Materials and Devices IV
15 August 2012 | San Diego, California, United States
Nanoepitaxy: Materials and Devices III
24 August 2011 | San Diego, California, United States
Nanoepitaxy: Homo- and Heterogeneous Synthesis, Characterization, and Device Integration of Nanomaterials II
1 August 2010 | San Diego, California, United States
Nanoepitaxy: Homo and Heterogeneous Synthesis, Characterization, and Device Integration of Nanomaterials
3 August 2009 | San Diego, California, United States
Nanomaterials Synthesis, Interfacing, and Integrating in Devices, Circuits, and Systems II
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