LOW-TEMPERATURE LASER-ASSISTED CBE-GROWTH OF ALGAAS

We report preliminary studies of low-temperature (335-400 degrees C) c hemical beam epitaxial (CBE) growth of AlxGa1-xAs on GaAs(0 0 1) using triethylgallium (TEG), trimethylaminealane (TMAA) and thermally precr acked Arsine (AsH3) as precursors. We also report results of Arf laser assisted chemical beam epitaxial growth over the same temperature ran ge. The growth rate for both assisted and unassisted growth as a funct ion of substrate temperature, laser power and precursor beam pressures was determined using laser reflectometry in which the Ar+ laser was a lso used as the probe. In the nonlaser assisted growth Al incorporatio n is observed to be significantly higher than would be expected at the normal growth temperature of 500 degrees C. With laser assistance the Al concentration, while higher than that at normal growth temperature s, is less than that without laser assistance and the growth rate is h igher. These observations, which extended Abernathy's early results to higher nominal Al concentration, are discussed in terms of the relati ve enhancement of the decomposition of TEG and the alane during laser assistance. Using literature values of the refractive index of AlGaAs alloys at the growth temperature, laser reflectometry was used to moni tor both composition and growth rate over a range of growth temperatur es. Reflectometry data were compared with the results of Auger Electro n Microscopy (AES) and Dektak stylus profiling. (C) 1998 Elsevier Scie nce B.V. All rights reserved.