Dopant ionization in silicon nanodevices investigated by Kelvin Probe Force Microscope

摘要

Dopant ionization was investigated by Kelvin Probe Force Microscope (KFM) measurements of surface potential of the thin silicon-on-insulator field-effect-transistor (SOI-FET) at different temperatures. In the resultant images it is observed that the surface potential is modulated by the temperature which indicates that the number of ionized dopant is changing. Also complementary simulation based on Poisson equation was performed. The results are qualitatively in agreement with the measured values. They show decreasing number of carriers when temperature is lowered. This result and interpretation are consistent with the previous freeze-out effect studies. However, direct observation of freeze-out effect hasn't been reported yet. We believe this is a significant progress towards single dopant observation.