In situ etching and regrowth in III-V molecular beam epitaxy for future nanotechnology

In this article, we present a combination of molecular-beam epitaxy (MBE) g rowth and in situ etching which allows the growth and manipulation of singl e atomic layers and small sized lateral structures on a nanometer scale. A solid source III-V:MBE system was extended with an in situ etching unit usi ng AsBr3 as the etching species. AsBr3 etching of GaAs provides a crystallo graphic selectivity which allows to produce extremely smooth (110) facets. Here, in situ AsBr3 etching is used with prepatterned substrates providing much smoother sidewalls as compared to only reactive ion etched samples. Su bsequent MBE overgrowth produces planar sidewalls and a very sharp and stra ight ridge on top of a mesa stripe. A slight backetching treatment on a pre grown sharp ridge provides a well-defined narrow and homogeneous plateau be yond the size limitation of standard lithography. These plateaus are used a s the template for subsequent MBE growth of quantum structures. First resul ts using this technique are demonstrated in a scanning electron microscopy study and photoluminescence measurements on InCaAs wires. Finally, we prese nt a lithographic technique which allows micropatterning of GaAs without th e use of any photoresist, different mask material, or prepattterned mesas. The native oxide surface layer is locally modified by UV light exposure and acts as a local mask in a following in situ etching procedure. (C) 2000 Am erican Vacuum Society.