Creation of GaAs microstructures using the nuclear nanoprobe LIPSION
We report on experiments concerning the fabrication of microdimensional structures in p- and n-type GaAs with different orientations using focused beams of high-energy protons and He+ ions and subsequent electrochemical etching. Depending on type and crystal orientation, the irradiated regions show a different etching behaviour resulting in different microstructures despite similar irradiation patterns. Single spot irradiation in (1 0 0) p-type GaAs results in the creation of small, elongated bumps while in ()-oriented, n-type material, a patterned formation of porous material was initiated by the irradiation. The effect of reduced etching of unirradiated material encircled by closed irradiated patterns up to a size of 25 µm, already known from Si, could be observed in GaAs as well. Furthermore, the creation of three-dimensional multilevel structures in (1 0 0)-oriented GaAs is demonstrated.