The document studies the structural and compositional evolution of self-assembled germanium islands on silicon during high growth rate LPCVD. Three samples were grown for different durations under identical conditions and characterized. For the shortest growth, small lens-shaped islands formed with few defects. For the intermediate sample, a mix of small and larger lens-shaped islands formed, indicating growth is dominant. For the longest growth, large square truncated pyramids replaced the smaller islands, decreasing the system's energy. Raman spectroscopy showed increasing Ge fraction and alloying with growth time. High growth rates delay preferred structures, but may control island structure and size distribution.