Growth and characterization of epitaxial FexAl1-x/(In,Al)As/InP and III-V/FexAl1-x/(In,Al)As/InP structures

We report on the growth of high quality epitaxial FexAl1-x on (In,A1)As/InP with x = 0.45-0.80 and thicknesses up to 1000 Angstrom, and on overgrowth of III-V semiconductor on the metal. Buffer layers of (In,A1)As were grown on InP substrates in a III-V growth chamber, then transferred to an attache d ultrahigh vacuum chamber with dual e-beam evaporators, where FexAl1-x lay ers were grown by co-evaporation. Despite a large lattice mismatch of simil ar to 1%-2% between the metal and the semiconductor, high quality layers of FexAl1-x with thicknesses of up to 1000 Angstrom were grown. The metal lay ers showed bright, streaky reflection high-energy electron diffraction patt erns, were specular under Nomarski microscopy, and had roughnesses of simil ar to 1-2 monolayers as measured by atomic force microscopy. High resolutio n x-ray diffraction showed that even at 1000 Angstrom, the layers were full y strained, and Pendellosung oscillations were observed, indicating high cr ystalline quality. Metal layers over similar to 200 Angstrom thick had resi stivities in the range of those expected of bulk layers (50-100 mu Omega cm ). Reflectivities greater than 90% for lambda = 4-20 mu m were observed for metal layers 1000 A thick. Overgrowth of (In,Ga)As and (In,A1)As on the me tal layers shows a marked sensitivity to As overpressure, possibly due to a n In surface-riding layer on top of the metal. (C) 1999 American Vacuum Soc iety. [S0734-211X(99)07203-0].