Silicon crystals grown by the CZ process have recently been studied with eddy current techniques to determine thermal profiles within the growing crystal. A key question concerning heat transfer in this semiconductor system during CZ growth is whether optical semitransparency in the infrared is important in affecting the high‐temperature thermal distribution within the crystal. From normal Fourier’s law calculations, well behaved profiles with rather flat radial isotherms are predicted in CZ growth. Eddy current data, though, show abrupt temperature changes near the crystal outer surface, indicating sharp radial thermal gradients. It is proposed that these sharp gradients are due in part to the onset of optical semitransparency in the crystal in the infrared. It is expected that such a transparency phenomenon will occur below a transition temperature. Any sharp gradients can be responsible for creep damage during growth.