JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS, vol. 4, no. 3, page. 773 - 783, 2002-09
JOURNAL OF APPLIED PHYSICS, vol. 92, no. 3, page. 1274 - 1279, 2002-08-01
JOURNAL OF LUMINESCENCE, vol. 99, no. 1, page. 73 - 77, 2002-08