Abstract

Recently, Knox and coworkers^1-3 have used time resolved absorption spectroscopy to study the relaxation kinetics of optically excited carriers in undoped¹, n and p modulation doped quantum wells^2,3. In these experiments, carriers were photoexcited using a 50fs pump pulse which generated electrons with an excess energy of approximately 20meV. Relaxation from the athermal photoexcited distribution to a relaxed equilibrium distribution was observed in the differential absorption with the characteristic relaxation times less than 200fs depending on the concentration and carrier type(n or p). Since the excess carrier energy is less than the optical phonon energy, relaxation in these experiments was argued to arise from carrier-carrier interaction.

© 1989 Optical Society of America