A comparative study of GaTlAs, InTlAs and GaInTlAs grown by SSMBE: the detrimental effect of indium

Epilayers of (Ga/sub 1-y/In/sub y/)/sub 1-x/Tl/sub x/As on InP(001), Ga/sub 1-x/Tl/sub x/As on GaAs(001) and In/sub 1-x/Tl/sub x/As on InAs(001) have been successfully grown using low-temperature solid-source molecular beam epitaxy (LT-SS-MBE). The epilayers have been fully characterised using reflection high energy electron diffraction (RHEED), Nomarsky optical microscopy (NOM), atomic force microscopy (AFM), double-crystal X-ray diffraction (DC-XRD) and Rutherford backscattering spectrometry (RBS). The study brings new information on the origin of the low incorporation rate of Tl atoms into III-V compounds and more precisely on the detrimental role of indium in this incorporation. In particular, it explains why only a maximum of 4% Tl is incorporated in a Ga/sub 0.47/In/sub 0.53/As matrix. This amount for a Ga/sub 0.47/In/sub 0.53/As matrix corresponds to the weighted mean of those for GaAs and InAs matrices, viz, /spl sim/7% and /spl sim/2.4%, respectively.