Confinement Levels in Passivated SiGe/Si Quantum Well Structures
The set of quantum confinement levels in SiGe quantum wells (QW) was observed in the temperature range from 80 to 300 K by means of charge deep-level transient spectroscopy (Q-DLTS) and transport measurements. These observations proved possible due to a passivation of structure surface with organic monolayer deposition. Si/SiGe/Si structures with different Ge contents in SiGe layer were studied. The confined levels in passivated structures became apparent through DLTS measurements as various activation energies in temperature dependence of the rate of carrier emission from QW. It was found that the recharging of SiGe QWs and carrier emission accomplish due to thermo-stimulated tunneling. The steps in the current-voltage characteristics originated from direct tunneling via the confined states were found to determine the current flow at high fields.
M. Kittler and H. Richter
I.V. Antonova et al., "Confinement Levels in Passivated SiGe/Si Quantum Well Structures", Solid State Phenomena, Vols. 156-158, pp. 541-546, 2010