Dresden 2003 – scientific programme
Parts | Days | Selection | Search | Downloads | Help
HL: Halbleiterphysik
HL 21: Neue Materialien
HL 21.4: Talk
Tuesday, March 25, 2003, 12:15–12:30, BEY/118
Non-intentionally-doped and sulfur-doped cBN single crystals: a photocurrent spectroscopy study — •Jose Antonio Garrido1, Stefan Kuch1, Christoph E. Nebel1, Martin Stutzmann1, and Takashi Taniguchi2 — 1Walter Schottky Institut, Technische Universität München, Am Coulombwall, 85748 Garching, Germany — 2Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
Non-intentionally-doped (n.i.d.) and sulfur-doped cubic boron nitride (cBN) single crystals prepared by high pressure / high temperature synthesis have been characterised by transport measurements. Both type of material exhibit n-type conductivity, with activation energies of 0.32 eV and 0.47 eV for S-doped and n.i.d cBN, respectively.
A shallow level with an optical ionization energy about 0.5 eV, as well as a deep level with an optical ionization energy of 3 eV have been detected in the n.i.d cBN by photocurrent experiments. The photocurrent spectrum of n.i.d cBN shows a pronounced maximum at an energy of about 3 eV, tentatively attributed to optical excitation of carriers in the defect level 3 eV below the conduction band.
The S-doped cBN crystal exhibits hopping conduction for temperatures below 200 K. A shallow optical ionization energy of 0.37 eV has been detected by photocurrent experiments, and it has been attributed to the effect of sulfur in the crystal.