AFM local oxidation nanopatterning of a high mobility shallow 2D hole gas
Abstract The recently developed AFM local anodic oxidation (LAO) technique offers a convenient way of patterning nanodevices, but imposes even more stringent requirements on the underlying quantum well structure. We developed a new very shallow quantum well design which allows the depth and density of the 2D gas to be independently controlled during the growth. A high mobility ( 0.5×10 6 cm 2 V −1 s −1 at 4.2 K) 2D hole gas just 350 A below the surface is demonstrated. A quantum point contact, fabricated by AFM LAO nanopatterning from this wafer, shows nine quantum steps at 50 mK.