In situ electron-beam processing for GaAs/AlGaAs nanostructure fabrications

The requirements for the fabrication technology of 2-dimensional and/or 3-dimensional nanometer-scale heterostructures with III-V compound semiconductors are described. In addition to a fabrication capability with nanometer accuracy, the processes must avoid both undesirable contaminations and any damage effect. To meet these requirements, we have developed in situ electron-beam (EB) processing in which all of the processes, including EB lithography, pattern etching and epitaxial overgrowth, are performed successively in an ultra-high vacuum-based environment. The present status of this technique, i.e. nanometer-scale patterning, cleanliness of the processed surfaces and damage-free characteristics, is discussed. It is also demonstrated that self-organized epitaxy, which is now being intensively studied, can be combined with in situ EB processing as an elemental process.