ATMI Inc. of Danbury, Conn., has signed a multimillion-dollar strategic alliance with Sterling Semiconductor Inc. of Sterling, Va., to develop and market silicon carbide wafers. Because of the material's unique electronic, thermal, physical and chemical properties, silicon carbide wafers are used in the development of blue and green light-emitting diodes and laser diodes for high-density optical memories. Under the agreement, ATMI's Epitronics business will license technology and transfer its ISO 9002-certified wafer manufacturing processes and equipment to Sterling. Sterling will sell and market the wafers.