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HL: Halbleiterphysik
HL 38: Poster III: Transporteigenschaften (1-14), Optische Eigenschaften (15-31), Grenz-/Oberfl
ächen (32-44), Heterostrukturen (45-57), Bauelemente (58-67), Gitterdynamik (68-69), Diamant (70), Raster-Tunnel-Mikroskopie (71)
HL 38.70: Poster
Thursday, March 30, 2000, 14:00–19:00, B
Electron Hole Drops in Synthetic Diamond — •Nikolai Teofilov1, K. Thonke1, R. Schliesing2, H. Zacharias2, R. Sauer1, H. Kanda3, and A. Zaitsev4 — 1Abt. Halbleiter Physik, Universität Ulm, 89069 Ulm — 2Physikalisches Institut, Universität Münster, D-48149 Münster — 3NIRIM National Institute for Research in Inorganic Materials, Tsukuba, Ibraki 305, Japan — 4LG Bauelemente der Elektrotechnik, Fern-Universität Hagen, D-58084 Hagen
Synthetic high temperature high pressure (HTHP) diamond crystals
were optically excited by laser pulses with photon energies above
the band-gap. At temperatures below 170K and high optical excitation
we observe novel broad luminescence bands in addition to the well-known
free exciton spectra with characteristic features identifying them as
originating from electron-hole drops (EHD). Line shape fits to the spectra
yield an electron hole density within the drops of n0 ≈ 9.6 1019 cm−3,
a reduced band-gap of Eg′= 5.224 eV (instead of Eg = 5.49 eV)
due to the attractive exchange and correlation of the particles
in the condensed phase. Fits to spectra taken at increasing
temperatures indicate that n0 decreases. The relationship n0(T)
defining the phase boundary curve between the liquid phase EHD and the
co-existence regime of EHDs and the gaseous phase, (the free excitons)
is discussed.