Pseudomorphic InGaAs Materials

Abstract : The objective of this program is to evaluate the dependence of pseudomorphic InxGa1-xAs quality on epitaxial growth conditions and InxGa1-xAs composition. All of the structures are fabricated by molecular beam epitaxy (MBE). The effects of different growth conditions are being evaluated with a combination of characterization techniques, including Hall effect, photoluminescence, transmission electron microscopy (TEM), and in-situ reflection high energy electron diffraction (RHEED). The electron spatial distribution and energy levels for quantized pseudomorphic structures are calculated self-consistently and compared with experiment. Critical layer thickness is shown to be a function of MBE growth temperature and the interruption of InxGa1-xAs growth with a few monolayers of GaAs is shown to smooth the InxGa1-xAs surface and provide strain energy relief, substantially extending the critical layer thickness. This new class of strained layer heterostructures which are here named thin strained superlattices (TSSL) extends the practical range of application of the GaAs-InxGa1-xAs system and is anticipated to be generally applicable to other strained layer systems. A publication describing the concept and demonstrating its practicality is tentatively scheduled for the May 22, 1989 issue of Applied Physics Letters. Also, results will be presented at the Electronic Materials Conference June 21-23, 1989 at the Massachusetts Institute of Technology. Keywords: Indium compounds, Aluminum gallium arsenide, Gallium arsenides.