# Münster 1999 – wissenschaftliches Programm

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# HL: Halbleiterphysik

## HL 37: Halbleiterlaser II

### HL 37.3: Vortrag

### Donnerstag, 25. März 1999, 16:30–16:45, H4

**Nonlinear Absorption and Gain in ZnSe** — •Q.Y. Peng, G. Manzke, and K. Henneberger — Fachbereich Physik, Universit"at Rostock, Universit"atsplatz 3, D-18051 Rostock

The physical nature of the gain in II-VI semiconductors is discussed controversially in the literature. While in [1] excitonic effects were deduced to be dominant in the gain region, experimental finding could be interpreted in terms of a strongly Coulomb-correlated electron-hole plasma (see [2]) too. We present calculations of the linear optical absorption and gain in ZnSe in a wide range of densities of the excited carriers and temperature based on the semiconductor Bloch equations considering all relevant many-particle effects as dynamical screening and both Coulomb and LO-phonon scattering. Including scattering processes between carriers and the coherent laser induced polarization (off-diagonal dephasing and effective interaction) [3] the correct position and linewidth of the exciton is described. Furthermore, the correct transition from gain to absorption at the chemical potential is guaranteed by introduction of Wigner distributions for the carriers. Our pure microscopic approach completely describes the experiments [1]: the optical gain in ZnSe appears in the vicinity of the 1s-exciton resonance. However, this evidence is found in terms of many-particle effects in a strongly Coulomb-correlated electron-hole plasma.

[1] J. Ding, M. Hagerott, T. Ishihara, H. Jeon, and
A. V. Nurmikko,

Phys. Rev. **B47**, 10528 (1993)

[2] K. Henneberger, H. G"uldner, G. Manzke, Q.Y Peng,
and M.F. Pereira, Jr., Advances in Solid State
Physics, **38**, (1998).

[3] G. Manzke, Q. Y. Peng, K. Henneberger, U. Neukirch, K. Hauke,
K. Wundke, J. Gutowski, and D. Hommel,
Phys. Rev. Lett. **80**, 4943 (1998).