Published online by Cambridge University Press: 21 February 2011
The dependence of the density of defects on the pressure ratio PAs/PGa and on the substrate temperature has been studied on a series of GaAs and GaAlAs samples prepared by MBE. Samples have also been desorbed prior to the MBE deposition by UV laser and the density of defects have been compared with the density of defects obtained in samples where thermal desorption occured. Optimum pressure ratios PAs/GPa and growth temperatures have been found for both GaAs and GaAlAs for minimum defect density. It is shown that insitu laser desorption, prior to MBE deposition is a feasible technique for attaining MBE structures with a low defect density, thus simplifying the substrate preparation process.