Optics with Semiconductors: Ultrafast Physics for Devices.
Abstract
We have established the exact nature of the various scattering processes between carriers and the many body effects that produce large nonlinearities near the bandedge of direct gap Ill-V semiconductors. The femtosecond optical nonlinearities near the bandedge of GaAs have been investigated after injection of very hot carriers with 2 eV photons. Instantaneous changes of refractive index and absorption coefficient have been found to be consistent with bandgap renormalization and screening of the Coulomb interactions. The combined effects of bandfilling, bandgap renormalization, plasma screening of the Coulomb interactions. and free carrier absorption leads to an optical response that may be exploited in device applications. At high injected densities, the dynamics of gain near the bandedge has been established. It is controlled by electron-electron and electron-hole scattering, and numbers for these effects have been obtained. The initial scattering of the hot carriers has been investigated by hole burning experiments in intrinsic p-type and n-type GaAs. In some cases, a very short scattering time (<25 fs) has been observed due to emission of coupled plasmon-phonon modes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 09, 1996
- Accession Number
- ADA316164
Entities
People
- Philippe M. Fauchet
Organizations
- University of Rochester