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HL: Halbleiterphysik
HL 31: Organische Halbleiter
HL 31.4: Talk
Thursday, March 29, 2001, 12:30–12:45, S16
Electronic transport and defect properties of PTCDA-modified Schottky contacts on sulfur-passivated GaAs(100) — •S. Park1, I. Thurzo2, Th. Lindner1, T.U. Kampen1, and D.R.T. Zahn1 — 1Institut für Physik, TU Chemnitz, D-09107 Chemnitz, Germany — 2Institute of Physics, Slovak Academy of Sciences, Bratislava, Slovak Republic
To modify conventional Schottky contacts, a thin layer of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) is employed between Ag and sulfur-passivated GaAs(100). Electronic transport and defect properties of this metal / organic semiconductor / inorganic semiconductor heterostructure are investigated using in situ current-voltage (IV) measurements and charge deep level transient spectroscopy (QDLTS). The additional surface dipole induced by the sulfur passivation on GaAs(100) is found to increase and decrease the barrier height of Ag/GaAs(100) Schottky contacts for n type and p-type, respectively. The passivation also influences the IV characteristic when PTCDA interlayer is introduced. The effective barrier height can be tuned between 0.54 0.73 eV by changing the thickness of the PTCDA interlayer. The QDLT spectra of in situ measured sample show a peak corresponding to GaAs bulk ET2 deep level while the density of deep levels caused by PTCDA interlayer is very low. However, the exposure of these Schottky contacts to air induces both shallow and deep levels in PTCDA that act as electron traps. The density of these levels is found to depend on the thickness of PTCDA layer.