Growth of germanium crystals by time-varing temperature profile, CVT methods

Germanium crystals have been prepared by chemical vapour transport (CVT), using three different procedures: the Stationary Temperature Profile (STP), the Linear Time- varying Temperature Profile (LTVTP) and the LTVTP followed by the Oscillatory Temperature Profile (OTP) in the same run. With the optimization of the growth parameters we have obtained a progressive increase of the crystal sizes and a reduction of the crystalline nuclei during the primary nucleation. The final result was only one crystal grown using the Linear Time-varying Temperature Profile associated with Oscillatory Temperature Profile (LTVTP+OTP). The crystals morphology observed by Scanning Electron Microscopy (SEM) shows details of their shape typical of cubic structure. The structural properties were studied by X-ray diffraction and indicate that all samples have the diamond cubic structure.