Abstract: A method for controlling dopant variation in neutron silicon is provided wherein the selection of undoped single crystal silicon for neutron transmutation doping is based upon certain criteria, for example, a maximum dopant difference which depends only on the desired uniformity of the neutron doped material and a maximum average dopant concentration which is a function of the homogeneity of both the undoped single crystal silicon and the neutron doped product. The results achievable from using the method for controlling dopant variation in the neutron doped silicon provides uniformity of the neutron doped product determinable by the correct choice of dopant difference and dopant factor, and that the doping precision for the radiated silicon does not depend on the doping factor.

Abstract: Apparatus and method for stabilizing and supporting a crystal semiconductor rod during fabrication refining from the action of a seed rod on a float zone melt of a crystalline rod source is provided wherein engageable fingers mounted in a vertically movable tube in axial register with the shaft holding the crystal seed rod are pivotally mounted in a non-horizontal upward position, the finger tips being force loaded for inward movement upon removal of a sleeve carrier so that the fingers engage, support, and stabilize the irregular cylindrical surface of the refined semiconductor rod. The tube and fingers are engageable through sleeve and tube piston means resulting in uniform stabilization and support of the crystal refined rod. The apparatus and method prevent the refined rod from vibrating and oscillating about its axis; thus allowing enlarged dislocation free crystal rod growth from a crystalline rod source, said refined crystal rod being grown on a slender seed rod.