Double Gate Bias Dependency of Low Temperature Conductivity of SiO2-Si-SiO2 Quantum Wells

The gate bias dependency of conductivity σ is examined in two Si quantum wells with well thickness tw = 7 run and tw = 14 nm. The conductivity of the thinner device behaves smoothly whereas the thicker device shows strong non‐monotonic features as a function of gate voltages. We show that a strong minimum in σ occurs close to the threshold of second sub‐band. Another minimum is seen at high electron density at symmetric well potential. This feature is addressed to sub‐band wave function delocalization in the quantization direction