Atomic layer epitaxy of germanium on silicon using flash heating chemical vapor deposition

Atomic layer epitaxy of Ge using GeH₄ decomposition at a surface heated with a Xe flash lamp in an ultraclean low-pressure environment was investigated. By use of a flash lamp light shot to separate the surface reaction and adsorption of Ge-hydrides, a single Ge atomic layer deposition per light shot has been realized under certain process conditions. It is found that the surface coverage velocity of Ge-hydride is higher at higher GeH₄ partial pressures and, in the adsorption equilibrium, the density of adsorbed Ge-hydride becomes nearly equal to that of the surface atoms in the investigated GeH₄ partial pressure range. From electron diffraction patterns, single crystallinity is found for the (100) substrate orientation, whereas deposited films are amorphous for the (111) orientation.