EPITAXIAL CRYSTALLIZATION DURING 600-DEGREES-C FURNACE ANNEALING OF AMORPHOUS SI LAYER DEPOSITED BY LOW-PRESSURE CHEMICAL-VAPOR-DEPOSITION AND IRRADIATED WITH 1-MEV XE IONS

The amorphous Si layers deposited by low-pressure chemical vapor depos ition on (100)-crystal-Si substrates and subjected to Xe-ion-beam irra diation are crystallized epitaxially in a layer-by-layer fashion to th e surface during 600 degrees C furnace annealing. Layer-by-layer cryst allization can be accomplished by irradiating the layers with a 1-MeV Xe-ion-beam for a 2 x 10(15)/cm(2) dose at 310 degrees C prior to furn ace annealing. In all cases during furnace annealing that amorphous Si layers are polycrystallized or are grown vertically in isolated epita xial-columnar-structures and then grown laterally into the amorphous r egion surrounding each column, the ion-beam-induced epitaxial crystall ization (IBIEC) method epitaxially crystallizes them in a layer-by-lay er fashion. This is because O atoms that were at the initial interface and that prevented layer-by-layer crystallization or columnar-epitaxi al-growth diffuse remarkably because of irradiation. This diffusion de creases the peak concentration and facilitates layer-by-layer crystall ization. O atoms at the interface are also diffused by irradiation wit h XO-keV P, 100-keV As, and 150-keV As ions. This diffusion results in the columnar growth during 600-800 degrees C furnace annealing. Wheth er layer-by-layer growth or columnar growth occurs during the furnace annealing depends on the peak concentration of oxygen at the interface . Direct evidence is shown that O diffusion is enhanced by the amount of inelastic electronic scattering of incident ion beam under the same elastic nuclear scattering conditions. The rates of IBIEC and of epit axial crystallization during furnace annealing after 1-MeV Xe-ion-beam irradiation for a 2 x 10(15)/cm(2) dose are affected by the amount of oxygen in the amorphous layer. The rate of layer-by-layer IBIEC using a 1-MeV Xe-ion-beam is nearly twice as high for a sample heated in th e deposition furnace after evacuation as it is for a sample heated bef ore evacuation. This difference is due to the smaller amount of oxygen in the amorphous Si layer of the former sample. (C) 1997 American Ins titute of Physics.