A focused ion beam vacuum lithography process compatible with gas source molecular beam epitaxy

Abstract

We demonstrate a direct-write lithography process for InP wafers in which a finely focused Ga+ ion beam is used to form the pattern which is then transferred into the substrate by dry etching. The result is a patterned substrate which is suitable for epitaxial growth. We have combined the ion beam writing and dry etching in a common vacuum chamber with a gas source molecular beam epitaxy (GSMBE) system. GaInAs/InP heterostructures grown on the in situ patterned substrates show excellent morphology and high luminescence efficiency. Surface relief on the order of 1000–2000 Å has been produced with this process using a 20 keV Ga+ ion beam. Lateral resolution is limited by the ion beam diameter, 2000 Å.