Film thickness dependence of dislocation density reduction in GaAs-on-Si substrates

Abstract

Low dislocation density (4×105 cm−2) GaAs films on Si substrates have been obtained with a GaAs film thickness of 180 μm using vapor mixing epitaxy based on GaCl-AsH3 (hydride) vapor phase epitaxy for the first time. Dislocation density decreases as the GaAs film thickness increases. Dislocation density is inversely proportional to film thickness in the film thickness region of <10 μm. However, in the film thickness region >50 μm (and/or of dislocation density <107 cm−2), dislocation density is exponentially proportional to the film thickness. Assuming that this dependence results from a dislocation reaction during GaAs growth, it can be interpreted that the dislocation-dislocation coalescence reaction mainly occurs with high dislocation density crystals, and additionally, a dislocation annihilation reaction, deflection, occurs with low dislocation density crystals.