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HL: Fachverband Halbleiterphysik

HL 56: GaN: Optical characterization

HL 56.2: Vortrag

Mittwoch, 13. März 2013, 12:15–12:30, H15

Band-gap renormalization versus Burstein-Moss shift in (0001) GaN investigated by spectroscopic ellipsometry — •Sarah Osterburg¹, Martin Feneberg¹, Eberhard Richter², Stephanie Fritze¹, Armin Dadgar¹, Alois Krost¹, and Rüdiger Goldhahn¹ — ¹Institut für Experimentelle Physik, Otto-von-Guericke-Universität Magdeburg — ²Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Berlin

High free electron concentrations in semiconductors lead to enhanced electron-electron and electron-ion interactions decreasing the fundamental band-gap of the material. On the other hand, the simultaneous filling of the conduction band shifts the Fermi level and thus the absorption onset to higher energies, counteracting the band-gap renormalization. The interplay of both effects is investigated in this study experimentally. Spectroscopic ellipsometry was employed on c-plane free standing HVPE grown GaN:Si samples (n≤ 1.4× 10¹⁹ cm⁻³) and c-plane GaN:Ge thin films grown on sapphire (3.8×10¹⁹ cm⁻³ ≤ n < 2× 10²⁰ cm⁻³). When taking into account the strain state, a complete picture is obtained which will be discussed