Silicon nanowire growth technologies for nanomechanical devices

Abstract

Silicon nanowires obtained via vapor-liquid-solid (VLS) mechanism offer many extraordinary properties for applications in nanomechanical devices. Their structural quality (low defect density, surface flatness) and unique mechanical properties (robust self-assembly, high stiffness, giant piezoresistance) together with, recent advances in growth control, promise to allow unprecedented performance of wide variety of systems. However, device fabrication is generally limited to prototype fabrication and more efforts to achieve simultaneous control of nanowire properties and location are needed._x000D_ This thesis has been focused towards the development of high yield/ large scale fabrication technologies based on catalyst grown Si nanowire to realize devices that exploit their exceptional properties. Fabrication technologies for the selective growth of silicon nanowire arrays and single nanowire on functional devices have been developed and posteriorly adapted for the fabrication of several nanowire based devices._x000D_ In particular, the design, fabrication and characterization of a piezoresistive cantilever in which the active sensor is composed of an horizontal Si nanowire array has been demonstrated. Giant piezoresistance coefficients characteristics of Si nanowires are translated into an increment in the cantilever mechanical sensitivity compared with similar bulk devices. On the other hand, the fabrication of nanomechanical resonators based on single nanowires for mass sensing applications with different transduction mechanims has been performed. The characterization of these devices proved that single nanowires are exceptional platforms to develop ultra-high sensitive mass sensors and to study fundamental properties of nanomechanical structures.

Date of Award	14 Sept 2012
Original language	English
Supervisor	Alvaro San Paulo Hernando (Director)