The Molecular Beam Epitaxy of Semiconductor Nanostructures

Molecular Beam Epitaxy (MBE) is a technique allowing one to fabricate complex semiconductor structures with accuracy on the atomic layer scale. The facility consists of a dual-chamber Riber 32-P MBE machine, one chamber dedicated to the growth of II-VI semiconductors, and one to the III-V growth. The II-VI and III-V chambers are inter-connected by an ultrahigh vacuum channel which allows transfer of wafers from the III-V to the II-VI chamber -- and vice-versa -- without exposure to the atmosphere. The facility is located in a well-furnished laboratory, with all the essential support systems (chemical and laminar flow hoods, dedicated liquid nitrogen supply, de-ionized water, etc.). The II-VI system is operating with seven solid-source effusion cells, loaded with Zn, Cd, Mn, Mg, Se, Te, and Cl (the latter for n-type doping). The III-V chamber contains Al, Ga, In, As, Sb, Mn, Be, and Si sources. Here Mn is for the growth of ferromagnetic semiconductors, and Be and Si is for p- and n-type doping. The cell shutters in both chambers are computer-controlled, and perform reliably in the MBE mode, as well as in the more demanding atomic layer epitaxy (ALE) and migration-enhanced epitaxy (MEE) modes. Characterization during growth is performed using a 10 KeV RHEED gun. The ability to transfer epitaxially-grown layers between the III-V and the II-VI chambers provides the opportunity for studying hetero-valent interfaces, as well as for the growth of II-VI layers on epitaxially grown III-V buffers, and vice-versa.