Quantum hall Effect in Ge1-xSix(111)Ge MQW samples of non-standard six-point contact geometry

Abstract We investigate the Quantum Hall Effect (QHE) in selectively boron-doped GeSi/(111)Ge multi-quantum well (MQW) samples of non standard geometry with six-point contacts disconnected from the sample edges. The Hall resistance shows a well-pronounced quantisation that is consistent with integral QHE (IQHE) value (h/ve 2 ) at temperature T = 4.2K. When the temperature was lower than 2.5K, unusual peaks on the R xy QHE plateaux were observed. We explain this behaviour by non-equilibrium population of Landau levels that results from the separation of current contacts from the edge of the sample.