Regensburg 2004 – scientific programme

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HL: Halbleiterphysik

HL 28: Optische Eigenschaften

HL 28.2: Talk

Wednesday, March 10, 2004, 15:30–15:45, H17

Dynamic band gap renormalization in Cu₂O studied on a µeV scale — •Giorgio Baldassarri Höger von Högersthal¹, Gregor Dasbach¹, Dietmar Fröhlich¹, Heinrich Stolz², Manfred Bayer¹, Robert Klieber¹, and Dieter Suter¹ — ¹Institut für Physik, Universität Dortmund, D-44221, Germany — ²Fachbereich Physik, Universität Rostock, D-18051, Germany

Owing to the large exciton binding energy and the long radiative lifetime, cuprous oxide (Cu₂O) is considered a prototype material for the study of excitons. Especially the quadrupole allowed lowest yellow exciton transition has always attracted much interest. This state has been recently investigated with ultra-high spectral resolution using a tunable single frequency dye laser, revealing extremely sharp exciton linewidths of < 1 µeV [1]. Here we investigate this system in the high density regime. Using pulsed excitation we get access to dynamic line shifts on a sub µeV energy scale and a ms time scale. The experiments show dynamic red shifts of the exciton transition as the excitation power is increased. These findings are explained by an absorption induced renormalization of the band gap.
G. Dasbach et al., Phys. Rev. Lett. 91, 107401 (2003).