Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 5: SiC

HL 5.1: Vortrag

Montag, 27. März 2006, 12:15–12:30, BEY 154

Electronic Raman Scattering of Phosphorus Donors in Silicon Carbide — •Martin Hundhausen, Roland Puesche, and Lothar Ley — Technische Physik, Universität Erlangen

We have studied temperature and polarization dependent electronic Raman scattering in phosphorus doped Silicon Carbide (SiC). We observe signals in the low temperature Raman spectra with Raman shifts between 2.2 meV and 5.3 meV depending on the polytype. We assign these energies to transitions between the donor 1s ground state to its valley-orbit split 1s excited state. Different valley-orbit energies are assigned to signals originating from donors substituting different inequivalent lattice sites of host Si atoms. The splitting results from the different symmetries of possible linear combinations of states at the nonequivalent conduction band minima of SiC. From the polarization dependence of the Raman signals for 6H- and 4H-SiC we conclude that the two possible 1s donor states belong to E₂ and A₁-symmetry of the C_6v point group of the crystal, respectively. The temperature dependent occupation of these states as monitored by the Stokes and Anti-Stokes intensities in the Raman spectra in combination with the known degeneracies g_A1 and g_E2 suggests that the A₁ state is the ground state.