Resonant tunneling in Si/SiGe/Si structures with a single quantum well under surface passivation

Si/SiGe/Si structures with single SiGe quantum wells (QWs) of different Ge content in the SiGe layer were studied at temperatures of 80 to 300 K. The structure surfaces were passivated with organic monolayers of 1 octadecene. The passivation removed the surface-defect charge resulting in a high hole population of SiGe QWs and made it possible to observe clearly the resonant tunneling of holes through confined levels in SiGe QW. The tunneling became evident as the steps on current-voltage characteristics. The energies of confined levels found from these data are consistent with calculated ones and with energies found from DLTS measurements. It was shown that the carrier emission from QWs is mainly caused by thermally activated tunneling at low biases and direct tunneling through the confined states at high biases. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3671058]