1. S.J. Pearton, Mater. Sci. Rep. 4, 313 (1990).
2. J.M. Zavada and D. Zhang, Solid State Electron. 38, 1285 (1995).
3. G.S. Pomerenke, P.B. Klein, and D.W. Langer, eds., Rare Earth Doped Semiconductors I (Pittsburgh, PA: Materials Research Society, 1993).
4. S. Coffa, A. Polman, and R.N. Schwartz, eds., Rare Earth Doped Semiconductors II (Pittsburgh, PA: Materials Research Society, 1996).
5. J. Zavada, T. Gregorkiewicz, and A.J. Steckl, eds., Rare Earth Doped Semiconductors III (Amsterdam, Elsevier, 2001).