Ballistic Electron Transport in the Plane

Abstract

A ballistic electron is that ‘lucky electron’ that succeeds traversing the solid without elastic or inelastic scattering events. The current interest in ballistic and quasi ballistic electron transport has emanated mostly due to the following characteristics of the transport: (a) Ballistic electrons move faster than diffusing ones, thus enabling the construction of high speed devices; (b) Ballistic electrons maintain their energy, direction, and phase, thus can interfere and be steered by electric or magnetic fields; (c) Ballistic electrons can be used as probes to study properties of semiconducting materials. These attractive features and the technology that has advanced rapidly have resulted in increased activities in the area of ballistic transport in the past few years. Significant recent discoveries in this arena were the direct demonstration of ballistic transport and the determination of the ballistic mean free path (mfp) via electron energy spectroscopy [1] in the ‘vertical domain’ (using hot electron transistors), and the observation of the quantized ballistic resistance [2] in the ‘horizontal domain’. Here we summarize our recent results [3,4,5] of hot electron spectroscopy in the plane of the 2DEG and describe results of ballistic hot electron transport with an unexpectedly long mfp.