Schematic of the fabrication process used to make micropillars and SEM image of an ensemble of micropillars with diameters ranging from .
Top: reflected laser intensity and flow rate as a function of time, during the etching of -height pillars. The flow rate is set to , RF power to and pressure to . Bottom: average etch rate of GaAs as a function of flow rate.
Cross-sectional TEM 002 dark-field image of micropillars (the diameters of the pillars are, respectively, 390, 250, and ) and energy dispersive x-ray microanalysis spectra obtained on the cladding layer of the pillars.
SEM images of the etched profile of the pillars for different flow rates. (a) High constant rate: The rate of is too high and the etching is completely inhibited, (b) low constant rate: The etched profile is isotropic (this is true only for undoped substrates; for - or -doped substrates, an anisotropic profile can be achieved with a constant flow rate), (c) flow rate ramp that is not steep enough, and (d) flow rate ramp that gives the desired anisotropic profile.
Spectra of micropillars with diameters ranging from .
Quality factor of our micropillars as a function of the diameter.
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