Ballistic Electron Transport in a Gated Constriction
It is now clear that the conductance of a short, narrow constriction in a 2DEG is quantised in units of 2e2/h1to8. This quantisation has so far only been demonstrated in short, split-gate FETs9 in which the width of the constriction can be continuously varied thereby changing the number of occupied quantum channels (subbands). Squeezing the constriction reduces the number of i occupied subbands and the resistance increases in a step like fashion with plateaus at values of R=h/2ie2. Split gates have been used in various configurations to demonstrate the magnetic depopulation of 1D subbands10, electron focussing11 and the non-additivity of ballistic resistors12. In this paper we show that the same quantisation exists in devices of constant width but variable carrier concentration (Fermi energy) and we discuss preliminary results from two devices of different aspect ratio.
KeywordsCarrier Concentration Gate Voltage Potential Step Depletion Width Narrow Constriction
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