1993, Electron. Lett., 29, 375, 10.1049/el:19930252
1993, Appl. Phys. Lett., 62, 1952, 10.1063/1.109501
1990, Phys. Rev. Lett., 65, 1929, 10.1103/PhysRevLett.65.1929
1991, Appl. Phys. Lett., 58, 2258, 10.1063/1.104915
1998, Appl. Phys. Lett., 72, 1745, 10.1063/1.121171
1995, Phys. Rev. B, 52, R11, 10.1103/PhysRevB.52.R11
1982, Solid State Commun., 41, 707, 10.1016/0038-1098(82)91121-8
1985, J. Phys. C: Solid State Phys., 18, 5629, 10.1088/0022-3719/18/29/013