Selectivity mechanism of all ultra high vacuum scanning tunneling microscopy based selective area growth

We describe a selective area growth based on ultra-high-vacuum UHV.–scanning-tunneling-microscopy STM.lithography. After nitridation of GaAs surfaces and selective depassivation by UHV–STM, an array of uniform 6.4"0.8-nm high GaAs dots was successfully grown on the depassivated areas 50 nm=50 nm.using trimethylgallium TMG. and tertiarybutylarsine. On the side walls of dots, 114.or 117.facets appeared. It was found that unintentional growth on the nitrided mask surface is due to TMG decomposition on the nitrided surface. The unintentional growth can be suppressed by using an amorphous-like nitrided surface and by increasing the thickness of the nitrided surface layer, and consequently the selectivity is improved. q1998 Elsevier Science B.V. All rights reserved