1 October 1990 Interfacet migration and defect formation in heteroepitaxy on patterned substrates: AlGaAs and InGaAs on GaAs (100) in MBE
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Proceedings Volume 1285, Growth of Semiconductor Structures and High-Tc Thin Films on Semiconductors; (1990); doi: 10.1117/12.20817
Event: Advances in Semiconductors and Superconductors: Physics Toward Devices Applications, 1990, San Diego, CA, United States
Abstract
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.
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Supratik Guha, Anupam Madhukar, Li-ping Chen, K. C. Rajkumar, Ravindra M. Kapre, "Interfacet migration and defect formation in heteroepitaxy on patterned substrates: AlGaAs and InGaAs on GaAs (100) in MBE", Proc. SPIE 1285, Growth of Semiconductor Structures and High-Tc Thin Films on Semiconductors, (1 October 1990); doi: 10.1117/12.20817; https://doi.org/10.1117/12.20817
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KEYWORDS
Gallium arsenide

Optical lithography

Semiconductors

Photomicroscopy

Thin films

Spatial light modulators

Indium gallium arsenide

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