BACK GATING OF A 2-DIMENSIONAL HOLE GAS IN A SIGE QUANTUM-WELL

A device comprising a low-resistivity, n-type, Si substrate as a back gate to a p-type (boron), remote-doped, SiGe quantum well has been fab ricated and characterized. Reverse and forward voltage biasing of the gate with respect to the two-dimensional hole gas in the quantum well allows the density of holes to be varied from 8x10(11) cm(-2) down to a measurement-limited value of 4x10(11) cm(-2). This device is used to demonstrate the evolution with decreasing carrier density of a re-ent rant insulator state between the integer quantum Hall effect states wi th filling factors 1 and 3. (C) 1997 American Institute of Physics.