We have used electron beam lithography in single level PMMA to investigate both ultra-submicron gate MESFETs and a novel quantum device called a BlochFET. From d.c. transconductance (gm) measurements of MESFETs with gate lengths from 35 to 65 nm, our data indicate a rise in gm below 50 nm which we attribute to the onset of velocity overshoot. The BlochFETs and HEMTs whose gates are replaced by a lateral surface superlattice grid structure. These grids are composed of 40 nm lines on 170 nm pitch. We have observed negative differential conductance which may be due to Bloch oscillation effects at low temperatures and believe this to be the first such observation yet reported.
ASJC Scopus subject areas
- Materials Science(all)
- Condensed Matter Physics
- Electrical and Electronic Engineering