Abstract: A method and apparatus for reducing branching, reducing defects, and improving the overall surface morphology of silicon on insulator (SOI) structures produced by Zone Melting and Recrystallization (ZMR) is described. A special heater for use in preparing SOI structures formed by ZMR comprises a graphite mass having corrugations extending along one or more side walls and which may be periodic. The heater provides concentrated regions of heat which vary periodically across the length of the molten zone of the SOI structure. Alternatively, the heater comprises a stationary lower heater member upon which the wafer is placed and a movable upper heater member having corrugations. ZMR is achieved by translating the corrugated upper heater member past the wafer. In yet another alternative, a well known strip heater having a uniformly shaped movable upper member is improved by replacing the upper member with a movable upper heater member having corrugations.