Mark A. Hadley

Fluidic self-assembly of silicon microstructures

Fluidic self-assembly is a new technique which makes possible the integration of devices fabricated using dissimilar materials and processes. The integration is accomplished by fluidically transporting trapezoidally shaped blocks made of one material into similarly shaped holes in a receptor substrate. In this paper, a systematic study of the FSA integration efficiency is presented. Blocks and holes were formed from silicon using anisotropic etching. Two different sizes were considered: large blocks of dimension 1.0 mm/spl times/1.2 mm, and small blocks of dimension 150 /spl mu/m/spl times/150 /spl mu/m. FSA was performed in either water or methanol using a bubble pump apparatus to recirculate blocks. FSA of large blocks resulted in 100% filling of a substrate containing 191 holes within 2.5 minutes. Similar experiments with small blocks and a substrate with a 64/spl times/64 array of holes yielded a fill ratio of 70%, due to undesirable adhesion of blocks to the substrate surface. Roughening the substrate resulted in a fill ratio of 90%. Also presented is a simple rate equation model of the FSA process, along with a discussion of which process parameters are important and how they can be optimized.

MOLECULAR BEAM EPITAXY GROWTH METHOD FOR VERTICAL-CAVITY SURFACE-EMITTING LASER RESONATORS BASED ON SUBSTRATE THERMAL EMISSION

A molecular beam epitaxy growth monitoring method is developed for distributed Bragg reflectors and vertical‐cavity surface‐emitting laser (VCSEL) resonators. The wavelength of the substrate thermal emission that corresponds to the optical cavity resonant wavelength is selected by a monochromator and monitored during growth. This method allows VCSEL cavities of arbitrary design wavelength to be grown with a single control program. This letter also presents a theoretical model for the technique which is based on transmission matrices and simple thermal emission properties. Demonstrated reproducibility of the method is well within 0.1%.