GOALI: Materials Integration of III-V Compounds for Electronic Device Applications

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This is a GOALI project with collaboration between UCLA and Northrop Grumman Space Technology (NGST, formerly TRW). The project addresses materials science research issues relevant to III-V semiconductor wafer bonded template substrates having high bulk resistivity and appropriate surface lattice constants for large lattice parameter materials, and with compatible thermal expansion coefficients. Research areas include: (i) bonding and polishing of the templates to a GaAs, InP, or silicon substrate, (ii) ion splitting (hydrogen-based) of InP and InAs substrates and InAlAs graded buffer layers, (iii) strain modeling and measurement of the composite structure to, for example, determine the influence of thermal expansion differences on the stability of the structures, (iv) epitaxial growth of strained layers and of device structures on wafer bonded substrates, and (v) electronic and structural characterization. Carrier transport, photoluminescence, infrared and x-ray imaging will be implemented, as well as transmission electron microscopy, and atomic force microscopy. Applications involve structures with an intermediate dielectric bonding layer. An objective is to develop III-V based wafer bond templates for subsequent epitaxial growth of device structures using non-compliant layers. Issues of layer exfoliation, polishing, thermal-mismatch induced strain, and stability during annealing and epitaxial growth will be studied, as will the electronic properties of wafer-bonded structures. An important component of the proposed research is quantification of defects formed in wafer-bonded structures under different processing conditions. The template layers to be used are InP, InAs, and InAlAs layers wafer-bonded to GaAs (or InP or silicon) substrates with silicon nitride bonding layers. The test vehicle to address the relationship between structural properties and electronic performance is a high electron mobility transistor (HEMT) structure fabricated using high indium mole fraction InGaAs channels grown on the template layers. %%% The project addresses basic research issues in a topical area of electronic materials with high technological relevance. An important feature of the project is the strong emphasis on education, with emphasis on integration of research and education. Broader impacts of the project include industrial collaboration, and collaboration with the UCLA Center for Excellence in Engineering and Diversity. Undergraduate and high school students will be involved in the project. Wafer bonding lessons will be developed for a Grassroots Science Program that targets 5th and 6th grade students with hands-on science demonstrations. Results from the research will also be highlighted in both undergraduate and graduate courses. The industrial GOALI collaborations will also broaden the educational experience of graduate students involved in the project, provide access to technologically advanced processing tools not widely available to university researchers, and increase technological exchanges through seminars and presentations. The multidisciplinary and collaborative nature of the project provides education and training in the areas of materials processing, characterization, and prototype device fabrication/operation.***