Patent DE-102009027436-A1 (DE)
Title: Growth of crystals made of electrically conductive melts, comprises crystallizing the electrically conductive melts into a diamond- or zinc blend structure, and introducing a crystal seed oriented in drawing direction into the melt
Inventor: CZUPALLA MATTHIAS
IPC: C30B15/22
Filed: 2009-07-02
Abstract: The method for the growth of crystals (1) made of electrically conductive melts, comprises crystallizing the electrically conductive melts (3) into a diamond blend structure or zinc blend structure, introducing a crystal seed oriented in [001]-drawing direction into the melt, heating the melt contained in a crucible (2), initiating a facet growth parallel to the drawing direction, removing the growing crystals from the melt, and generating defined radial temperature gradients, in which two magnetic traveling fields running in a predetermined direction are produced. The method for the growth of crystals (1) made of electrically conductive melts, comprises crystallizing the electrically conductive melts (3) into a diamond blend structure or zinc blend structure, introducing a crystal seed oriented in [001]-drawing direction into the melt, heating the melt contained in a crucible (2), initiating a facet growth parallel to the drawing direction, removing the growing crystals from the melt, and generating defined radial temperature gradients, in which two magnetic traveling fields running in a predetermined direction are produced and the magnetic traveling fields are brought into the melt for impact. The radial temperature gradient is below 1 K/cm. The facet growth of the surfaces is initiated with a facet width (d), where a cross-section surface of the removed crystals has a quadratic shape vertical to the drawing direction. The magnetic traveling field upwardly running from below or downwardly running from top is generated in the melt and the magnetic traveling field inwardly running from outside or outwardlyrunning from inside is produced in the melt. The heating of the melt and the production of the magnetic traveling fields are carried out by two combined heater-magnetic field-arrangements, is carried out over a control of a parameter such as phase angle, frequency and/or current strength of supplied alternating current and/or direct current, and is carried out separately from each other using heating devices and magnetic field arrangements. A frequency of 5-1000 Hz and a phase angle of 1-120[deg] are set for producing the magnetic traveling fields. The control of the parameter is temporarily constantly or temporarily variably carried out for producing the magnetic traveling fields. The magnetic traveling fields run to each other where the magnetic traveling field downwardly running from top is generated in the melt and a further magnetic traveling field outwardly running towards a crucible wall (2a). The magnetic traveling fields run away from each other where the magnetic traveling field upwardly running from below is generated in the melt and a further magnetic traveling field inwardly running towards a crucible axis (2c). An electrical direct current is supplied through the melt, phase boundary and crystal. In the case of growth of compound semiconductor crystals, a device for reducing the temperature gradients is introduced. The crucible rotates with a predetermined speed during the drawing process or does not rotate during the drawing process. An independent claim is included for a device for the growth of crystals made of electrically conductive melts.