New Nanometric Opportunities with High Mobility Semiconductors such as InAs

Abstract

One-dimensioned electron gas (1DEG) structures can be fabricated from suitable hetero-structure sandwiches by using nano-technology Schottky- or MOS lithography. We have grown by MBE InAs sandwiched nearly lattice matched between AlSb and GaSb layers and obtained for InAs thicknesses of around 15 nm a room temperature mobility of up to 32000cm2/Vs, provided that the heterojunction was of InSb type. At 77K the electron gas has a mobility of up to 225000 cm2/Vs. Si-Nanowires are found to have an interesting band structure, which is different from Si bulk material. The InAs 1DEG exhibits a quantum-physical behaviour at low temperatures of a reasonable well defined quantized staircase conductance of a ballistic electron wave with increasing applied voltage. InAs is a material where such behaviour is expected to occur at not too low temperature. If two such 1DEG structures of slightly different geometry in parallel are applied with a triangular voltage, the difference potential between each of these two 1DEG’s is a pulse sequence. The number of pulses obtained then depends on the amplitude of the triangular voltage. This can be considered as a basic unit for an Analogue-Digital Converter. These concepts were initially outlined by us at one of the European workshops, intended for discussion of new ideas. Such nano-conductance lines and zero-DEG quantum dot electronic structures can be interconnected in such a manner that various types of signal processing can be achieved.