Test structures have been grown onto SiGe virtual substrates, with the first being to identify the effect on quantum well morphology of increasing Ge concentration have used a combination of energy dispersive X-ray microanalysis, electron energy-loss imaging and scanning transmission electron microscopy to measure the compositions of the various quantum wells. There is increasing interest in developing optical device structures in the far infrared (THz) region of the electromagnetic spectrum, an area that until had been relatively inaccessible for many science and engineering applications. The significant interest stems from possible applications relating to imaging and sensing in medical-related areas. Transmission electron microscopy and scanning transmission electron microscopy have been used to characterize the microstructure of quantum wells grown over a range of different germanium concentrations. Quantum well structures subsequently grown onto a 20% SiGe virtual substrate with a Ge concentration of 30% were found to be highly uniform and free of morphological distortions.