Structural properties of MBE grown GaMnAs layers

GaMnAs layers with Mn content varying from 0.25 to 3.5% and thickness from 0.2 to 1.0 mu m have been grown by molecular beam epitaxy (MBE) on GaAs (10 0) substrates. The Mn content was estimated both from in situ reflection hi gh energy electron diffraction (RHEED) and ex situ high resolution X-ray di ffraction (XRD) measurements. The samples have been grown in an MBE system connected to a photoelectron spectrometer system at the MAX-lab storage rin g. Our, photoemission, XRD and RHEED studies show that GaMnAs form uniform, ternary compound without any signs of MnAs precipitations. The samples wit h Mn content of 1.5-3.5% showed the ferromagnetic phase transition in the t emperatures 15-50 K depending on composition. We have done precise measurem ents of the lattice parameter both in surface plane and perpendicular direc tions. The reciprocal space maps show that GaMnAs layers are fully strained to the GaAs (100) substrates and their structural perfection is comparable to that of the low temperature GaAs buffer layer. (C) 2000 Elsevier Scienc e S.A. All rights reserved.