Voltaix, a semiconductor chip and solar cell company located in Branchburg, N.J., announced that Mark K. Fine will become interim chief executive officer, effective Jan. 1, 2010. Fine, 49, has more than 20 years of experience in the semiconductor and specialty chemicals industries. He previously served as president of Epichem Inc., which today is a division of Sigma Aldrich Corp. In connection with the appointment of Fine, Voltaix’s founder, Dr. John P. de Neufville, 69, will step down as CEO and will continue to serve as president, chief scientist and chairman of the company’s executive committee. Voltaix also announced that Matthew Stephens, who has been chief operating officer since 2003, is leaving the company to assume that role at Metem Corp., a Parsippany, N.J., developer of turbine technologies for aerospace and power applications.