Quantum hall effect in selectively doped strained p-Ge/Ge1-xSix superlattices

The Quantum Hall effect was observed in p-Ge/Ge 1-x Si x superlattices for the first time. The structures were prepared by the CVD method and their parameters are: composition x = 0.1 to 0.18; number of layers n = 30 to 100; hole concentration p = (5 to 10) × 10 11 cm -2 and hole mobility μ p = 15000 cm 2 /(Vs) at liquid helium temperatures. The hole concentration is determined by the concentration of B impurities introduced in the centre of Ge 1-x Si x layers which, due to the band offset, give holes in the Ge layers. Observed Quantum Hall peculiarities can be connected with an interaction between states of the two valence subbands split due to the strain caused by lattice mismatch and between two 2D levels one of which is occupied by holes.