EVIDENCE OF PHONON-ABSORPTION-ASSISTED ELECTRON RESONANT-TUNNELING IN SI/SI1-XGEX DIODES

We report a study of temperature dependence of electron resonant tunneling diodes in an Si/Si1-xGex material system grown by rapid thermal chemical vapor deposition. Up to four highly symmetric resonances were observed, but the lowest energy resonance has an anomalous temperature behavior, decreasing in strength with decreasing temperature below 140 K and entirely disappearing below 50 K. The temperature behavior and bias position of the resonance are consistent with a model of phonon-absorption-assisted tunneling with a phonon energy of 14+/-2 meV. The phonon is thought to be an acoustic phonon which promotes Umklapp scattering between the conduction band minima in the emitter and quantum well states.