Growth and Properties of III-VI Heterostructures

University Of Washington, Seattle WA

Investigators

Abstract

This project focuses on heteroepitaxial growth of III-VI based semiconductors and on interrelated structural, electronic, and optical properties of this class of materials. The research seeks to elucidate mechanisms of III-VI thin film growth, and to develop III-VI growth technology and materials characterization to the stage where these materials may be utilized for optoelectronic applications. Interface compounds based on III-VI materials will be used to control heteroepitaxy of both III-VI and more standard electronic materials, including their use to promote both laminar and islanded nanostructure formation. Problems associated with bulk III-VI materials, poor mechanical and thermal properties, are being addressed through use of thin films on substrates such as Si, GaAs and CaF2 . Development of this new generation of materials requires new, basic knowledge about the interacting constraints that control their electronic, optical and structural properties. This project strives to elucidate the role of these constraints through studies of heterointerface formation between common electronic materials and III-VI based materials. Primary goals are: to establish an experimental and theoretical framework based on nanoscale heteroepitaxial growth processes to optimize structural, electronic and optical properties of III-VI heterostructures; to exploit III-VI interface compounds to control semiconductor nanostructure formation; to evaluate structural, electronic, and optical properties of III-VI-based heterostructures for feasibility in novel optoelectronic applications. The approach is to concentrate in two areas: (i ) nucleation, growth and properties of GaxSey, AlxSey , and their alloys on Si(111), Si(100), GaAs(100), and CaF2 (111), and (ii) use of the resultant thin films as substrates for a) laminar and islanded growth of GaAs and ZnSe and b) GaxSey - Alx Sey superlattices. Growth kinetics, morphologies and quantum dot properties will be studied with nanoscale resolution using in situ scanning probe microscopy, UHV-transfer photoelectron spectroscopy and near-edge x-ray absorption, and ex situ high resolution transmission electron microscopy and energy loss spectroscopy. Area-averaged properties will be probed using photoelectron spectroscopy and diffraction, electron diffraction, ion scattering spectroscopy, and optical spectroscopies (photothermal, reflection-transmission, photoluminescence, and Raman scattering). %%% The project addresses basic research issues in a topical area of materials science having high potential technological relevance. The research will contribute basic materials science knowledge at a fundamental level to new aspects of electronic/photonic devices. The basic knowledge and understanding gained from the research is expected to contribute to improving the perform-ance and stability of advanced devices and circuits by providing a fundamental understanding and a basis for designing and producing improved materials, and materials combinations. An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area. ***