1. D.V. Lang: J. Appl. Phys. 45, 3023 (1974)
2. Topics Appl. Phys.;D.V. Lang,1979
3. G. Pensl: In Landolt-Börnstein, New Series III/22b, ed. by M. Schulz (Springer, Berlin, Heidelber 1989) p. 51ff.
4. J.W. Petersen, J. Nielsen: Appl. Phys. Lett. 56, 1122 (1990)
5. M. Lang, G. Pensl, M. Gebhard, M. Uhrmacher: Verhandl. DPG(VI) 25, 824 (1990)