화학공학소재연구정보센터
Journal of Vacuum Science & Technology B, Vol.18, No.3, 1557-1561, 2000
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) growth and in situ etching which allows the growth and manipulation of single 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 using AsBr3 as the etching species. AsBr3 etching of GaAs provides a crystallographic 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. Subsequent MBE overgrowth produces planar sidewalls and a very sharp and straight ridge on top of a mesa stripe. A slight backetching treatment on a pregrown sharp ridge provides a well-defined narrow and homogeneous plateau beyond the size limitation of standard lithography. These plateaus are used as the template for subsequent MBE growth of quantum structures. First results using this technique are demonstrated in a scanning electron microscopy study and photoluminescence measurements on InCaAs wires. Finally, we present a lithographic technique which allows micropatterning of GaAs without the 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.