Morphology of low-temperature homoepitaxial growth on laser-textured Ge(001)

We delineate the growth conditions of temperature, substrate vicinality, and hydrogen termination that produce rough and smooth crystal growth of Ge by molecular beam epitaxy. Ge(001) substrates are modified by laser texturing to produce all azimuths of miscuts θ in the range θ° < θ < 10° within a 4 μm diameter laser dimple. We deposit Ge on these modified substrates over a wide range of growth temperatures 150 °C < T < 400 °C, with and without an atomic hydrogen flux of 3 × 10 ¹³ cm^-2 s^-1, and characterize the morphologies by atomic-force microscopy. Ridge-shaped growth instabilities dominate the morphology for miscuts toward (110) directions; in regions with miscuts toward (100) the morphology is relatively smooth. Hydrogen flux suppresses the growth-mound instability at small miscuts and reduces the epitaxial critical thickness at large miscuts.