Gregory L. Williams has been appointed to the AMI Semiconductor board of directors. Williams is the executive chairman of Intersil Corp.'s board of directors and was previously president and CEO of Intersil.   . . .   Applied Materials Inc., a supplier of high-current ion implanters, announced it has shipped more than 100 Quantum implant systems, used in 300 mm chip manufacturing.   . . .   Ashok Dhawan was named president and CEO of electronics components maker Inphi Corp., succeeding Loi Nguyen, who will continue in his position as vice president of technology.