(19)

(11)

EP 0 641 488 A1

(12)

(43) Date of publication: 08.03.1995 Bulletin 1995/10 (21) Application number: 93913986.0 (22) Date of filing: 18.05.1993

(51) International Patent Classification (IPC):  H01L 29/ 84( . ) H01L 41/ 09( . ) H01L 41/ 08( . ) (86) International application number: PCT/US1993/004743 (87) International publication number: WO 1993/024963 (09.12.1993 Gazette 1993/29)

(84) Designated Contracting States: DE FR GB (30) Priority: 22.05.1992 US 19920888338 (71) Applicant: TRUSTEES OF BOSTON UNIVERSITY Boston, MA 02215 (US)	(72) Inventor: SMITS, Johannes, G. Quincy, MA 02169 (US) (74) Representative: Greenwood, John David, et al  Graham Watt & Co. Riverhead Sevenoaks Kent TN13 2BN Sevenoaks Kent TN13 2BN (GB)