NANOSTRUCTURE FABRICATION IN INP AND RELATED-COMPOUNDS

Nanometer-scale gratings have been fabricated in InP and InGaAs/InP heterostructures using electron-beam lithography and reactive-ion etching in methane-hydrogen plasmas. It is shown that the slight overcut obtained in the etch profiles during a single-step etch in CH4/H-2 is due to polymer formation on inert mask surfaces and edges. Intermittent removal of the deposited polymer film is shown to be effective in obtaining anisotropic profiles. Highly anisotropic 35-nm-wide InP lines at 70-nm pitch demonstrate the potential of this fabrication process. The formation of 100-nm-wide free-standing InP wires is also presented.