Comparison of nanomachined III–V semiconductor substrates

Abstract

Emerging device applications demand surface features on the order of hundreds of angstroms. Nanolithography by machining with a diamond tip is proposed as a means to reproducibly pattern semiconductor surfaces on this scale. This technique has already been shown to produce controlled features with depths down to 10 Å on GaAs [S. H. Goss et al., J. Vac. Sci. Technol. B 16, 1439 (1998)]. In this technique, a diamond tip is scanned along the sample surface with a constant force to produce the desired features. In this article we show the observed quality and reproducibility achieved by this technique in the patterning of several semiconductor substrates. The substrates patterned and examined include GaAs, GaSb, GaP, and InP. The samples were machined at a series of loads ranging from 9.8 to 196 μN. After machining they were cleaned with an appropriate solvent and supercritical CO2 to remove debris caused by the machining. The resulting patterned surfaces were characterized with an atomic force microscope. Lateral resolutions as good as 100 Å were successfully achieved illustrating the ability of this technique to achieve the dimensions required to form quantum dots. Line profiles indicated cut depths ranging from 5 to 500 Å. A near linear trend was observed in the depth of cut versus applied force over the investigated range for most of the substrates. The exact slope and intercepts were material dependent.