Temperature dependence of surface morphology of chemical vapor deposition grown Ge on Ge substrates

A step by step development of surface morphology as a function of deposition temperature (617–897 °C, by 40 °C steps) of Ge crystals grown by chemical vapor deposition using GeH4 in an He atmosphere is experimentally demonstrated. Three temperature regions are observed. A net‐like rough surface morphology composed of many interconnected elongated crystals is observed in the low temperature range (617–697 °C). In the high temperature range (817–857 °C) isolated islands of three‐dimensional structures having a pyramid‐like geometry and their interactions are observed. The medium range (737–777 °C) is found to be a transition between the above ranges. As a whole, the degree of surface order obtained increases with the deposition temperature. The mechanisms influencing the morphology are explained by the temperature dependence of the GeH4 decomposition rate, Ge atom, surface mobility and migration length, nucleation and re‐evaporation rates, activity of surface defects and nucleation sites, and finally, parasitic oxide formation.