We grew SiGe on insulator (SGOI) by the rapid melt growth (RMG) technique. The RMG method combines Si-seeded, defect-necked melt growth with liquid encapsulation by self-aligned silicon dioxide microcrucibles. We obtained high quality, single-crystal, and (100)-oriented laterally graded SGOI structures with this simple and robust process, demonstrating that RMG can be applied to alloys with large miscibility gaps. Our process opens the possibility of building Si-compatible devices that require a smooth lateral variation in bandgap or lattice constant. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3436665] All rights reserved.