Growth and characterization of DyP/GaAs and DyAs/GaAs-based heterostructures and superlattices

Details of the structural and electrical properties of epitaxial DyP/GaAs and DyAs/GaAs is reported. DyP is lattice matched to GaAs, with a room temperature mismatch of less than 0.01%. DyAs, on the other hand, has a mismatch of nearly 2.4%, Both DSIP and DyAs have been grown by solid source MBE using custom designed group V thermal cracker cells and group III high-temperature effusion cells. High-quality DyP and DyAs epilayers, as determined by XRD, TEM, and AFM analysis, were obtained for growth temperatures ranging from 500 degrees C to 600 degrees C with growth rates between 0.5 and 0.7 mu m/h. The DyP epilayers are n-type with measured electron concentrations of the order of 3 x 10(20) to 4 x 10(20) cm(-3). with room temperature mobilities of 250-300 cm(2)/V s, and with a barrier height of 0.75 eV to GaAs. The DyAs epilayers are also n-type with concentration of 1 x 10(21) to 2 x 10(21) cm(-3), with mobilities between 25 and 40 cm(2)/V s. DyP is stable in air with no apparent oxidation taking place, even after months of ambient exposure to untreated air. (C) 1998 Elsevier Science B.V. All rights reserved.