A method and apparatus for forming a sheet are disclosed. A melt is cooled and a sheet is formed on the melt. This sheet has a first thickness. The sheet is then thinned from the first thickness to a second thickness using, for example, a heater or the melt. The cooling may be configured to allow solutes to be trapped in a region of the sheet and this particular sheet may be thinned and the solutes removed. The melt may be, for example, silicon, silicon and germanium, gallium, or gallium nitride.