Increased axial temperature gradients and growth rates resulted in the segregation of unwanted absorbing defects to the edges of single crystals which were produced by using the horizontal gradient freeze technique. Long-wavelength infra-red imaging of polished boules revealed a clear central core which exhibited absorption losses that were 26 times lower than those in the darker edge-regions. This pronounced segregation was attributed to the preferred incorporation of native defects at facets that formed near to the side-walls of the horizontal boat.

Defect Segregation in CdGeAs2. P.G.Schunemann, S.D.Setzler, T.M.Pollak, A.J.Ptak, T.H.Myers: Journal of Crystal Growth, 2001, 225[2-4], 440-4