AFM local oxidation nanopatterning of a high mobility shallow 2D hole gas

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 x 10(6) cm(2) V-1 s(-1) at 4.2 K) 2D hole gas just 350 Angstrom below the surface is demonstrated. A quantum point contact, fabricated by AFM LAO nanopatterning from this wafer, shows nine quantum steps at 50 mK. (C) 2003 Elsevier Science Ltd. All rights reserved.