Electron Tunneling Times in Coupled Quantum Wells

The work by Esaki and Tsu on tunneling in superlattices1 has generated a considerable interest for the potential application of tunneling to real devices. The rapid progress of epitaxial growth techniques has led to the creation of novel semiconductor structures which exhibit quantum-size effects and tunneling such as the double-barrier resonnant tunneling structures or the superlattice p-i-n diodes2. Transport studies in these structures demonstrated Bloch transport through the superlattice minibands3, negative differential resistance in double barrier diodes4, field induced localization5. More recently, optical measurements have been performed in double barrier structures in order to gain some insight on space-charge buildup6 and escape rates7.