2:15 PM - 2:30 PM
▼ [21p-135-6] Pole figures as tools for understanding film misorientation in Group IV thin films fabricated by aluminum-induced crystallization
Keywords:Silicon, Aluminum-induced Crystallization, Epitaxy
Si and Ge(111) films with >95% surface orientation fabricated by aluminum-induced crystallization have been realized in recent years. These substrates are attractive for subsequent homo-and heteroepitaxy, but the standard characterization methods for these films do not give clear information about the suitability of the surfaces for subsequent epitaxy. Here, we discuss how analysis of pole figures from electron backscatter diffraction (EBSD) can give a qualitative but clear evaluation of the misorientation of AIC-Si films and their suitability for subsequent homo or heteroepitaxy. AIC-Si films were fabricated by depositing ~30nm of Al onto fused quartz substrates. Following a brief air exposure, ~30nm of amorphous silicon was deposited. Subsequent annealing at temperatures from 425-500°C formed crystalline silicon thin films. For some samples, aluminum was etched prior to EBSD, while for other samples the aluminum was removed and then MOCVD growth of GaN was performed.
EBSD pole figures illustrate clear differences in film quality for samples annealed under identical conditions but with different degrees of misorientation. Highly misoriented films show a diffuse diffraction ring corresponding to the (111) direction, while reduced misorientation results in a much sharper band. Subsequent x-ray rocking curves of GaN films grown on these substrates shows that AIC-Si misorientation is translated directly into GaN misorientation. The pole figures can also be used to illustrates the effect of processing conditions such as annealing temperature on film misorientation, with decreasing misorientation observed as annealing temperatures decrease from 500 to 425°C. Thus through use of the EBSD pole figure, the effect of fabrication conditions on AIC film quality can be observed and conditions can be subsequently optimized.
EBSD pole figures illustrate clear differences in film quality for samples annealed under identical conditions but with different degrees of misorientation. Highly misoriented films show a diffuse diffraction ring corresponding to the (111) direction, while reduced misorientation results in a much sharper band. Subsequent x-ray rocking curves of GaN films grown on these substrates shows that AIC-Si misorientation is translated directly into GaN misorientation. The pole figures can also be used to illustrates the effect of processing conditions such as annealing temperature on film misorientation, with decreasing misorientation observed as annealing temperatures decrease from 500 to 425°C. Thus through use of the EBSD pole figure, the effect of fabrication conditions on AIC film quality can be observed and conditions can be subsequently optimized.