Carrier escape time in quantum well lasers: dependence on injection level, doping concentration, and temperature

The transport of carriers along the confinement region, the carrier capture into and the carrier escape out of quantum wells (QWs) are very important processes to be taken into account in order to properly understand the DC and high-frequency properties of QW lasers. These processes can seriously limit the maximum achievable modulation bandwidth. Therefore, it is of great interest to determine the experimental values of the capture and escape time constants, tau(cap) and tau(esc)which govern such phenomena. It is also desirable to find simple theoretical expressions relating the time constants with the laser structure and working conditions. In order to obtain information about the carrier dynamics, we have performed high frequency impedance measurements for GaAs-based lasers with different geometries, barrier heights and doping concentrations. We have experimentally observed an increase of tau(esc) with both the p-doping concentration and nominal barrier height, as well as an exponent ial dependence of tau(esc) on the inverse temperature.