Formation of a transient Si hydride multilayer and recrystallization of a Si-Si network during vacuum-ultraviolet-excited Si homoepitaxy from Si2H6

The mechanism of vacuum-ultraviolet-excited Si epitaxy on Si(100) from Si2H6 has been clarified by spectroellipsometric measurement. The crystallinity evolution, classified into three types which depend strongly on the photon flux, is discriminated by distinct shapes of (Psi,Delta) trajectories. The formation of a Si hydride multilayer at the outermost surface was evidenced by the immediate changes in the: (Psi,Delta) angles when Si7H6 is introduced. This layer is decomposed quickly when the Si2H6 supply is terminated. The Si hydride layer is then converted into a crystalline Si-Si network involving voids due to the photon-stimulated desorption of H atoms. For the epitaxy is to be maintained, the vacuum-ultraviolet-stimulated rearrangement of the Si-Si network into a dense Si crystal must further occur at a higher rate than deposition of Si hydrides. [S0163-1829(99)02604-1].