TnAs quantum dots were deposited onto GaAs or onto a thin (nominally 7 ML) InxGa1-xAs layer (x = 0.075 or 0.15) by metal-organic chemical vapor deposition and compared using photoluminescence measurements, plan-view transmission electron microscopy (TEM) and atomic force microscopy (AFM). The photoluminescence intensity was considerably reduced for samples grown using an InGaAs buffer layer. This is correlated with the formation of dislocations (density = 1.5(+/- 1) x 10(8) cm(-2)) making them unsuitable for incorporation into devices requiring high optical efficiency. (c) 2005 Elsevier B.V. All rights reserved.