Effects of a Native Oxide Layer on the Carrier Mobility and Void Formation at Aluminum-Induced Crystallization of Amorphous Silicon

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In the present study, the effects of the native oxide layer that forms between an amorphous Si (a-Si) layer and a microcrystalline Al layer in the coating processes on the crystallizations of a-Si, the microstructure at the mixing layer [ and microcrystalline Si at the a-Si layer], and the carrier mobility of the film produced by aluminum-induced crystallization are investigated. The effect of the film on Si crystallization was also investigated by varying the thickness of the Al film in the specimens without a native oxide layer. The absence of a native oxide layer at the interface of the and a-Si layers allowed Si crystallizations at a lower annealing temperature and a shorter annealing time, and increased the carrier mobility significantly. A sufficiently large film thickness was required for Si crystallization in the specimens without a native oxide layer; however, an excessive thickness deteriorated the crystallization behavior. The native oxide layer detected using X-ray photoelectron spectroscope was a barrier for the penetration of into the a-Si layer. Si crystallizations were often accompanied by voids of various sizes and densities. The carrier mobility generally decreased with increasing void size and density of voids.