Abstract Thick films of InxGa1 - xAs (x = 0.53 ± 0.04) have been grown on misoriented silicon substrates by molecular beam epitaxy as a function of substrate temperature and layer thickness. For films of 3 μm thickness, grown in the temperature range Tg = 200 to 550°C, the films became increasingly rough as the growth temperature was raised and the full width at half maximum of the double crystal X-ray diffraction features were very broad (more than 1000 arc s). In most cases these diffraction features were symmetric, but for growth in a small temperature window around 350°C highly asymmetric peaks were observed due to variations in the tilt angle between the (100) lattice planes of the substrate and epitaxial layer. The magnitude and direction of the tilt angle were found to be highly dependent on growth temperature being directed away from the substrate normal for Tg around 350°C but towards the substrate normal for higher substrate temperatures. A variable thickness study performed at 350°C showed that the maximum tilt angle increases approximately linearly with thickness, reaching a value of about 7500 arc s for layers 8 μm thick.