Photocarrier escape time in quantum-well light-absorbing devices: Effects of electric field and well parameters

We analyze the dependence of the carrier escape time from a single-quantum-well optoelectronic device on the aplied electric field and well width and depth. For this purpose, a new simple and computationally efficient theory is developed. This theory is accurate in the case of electrons, and the assessment of the applicability for holes is given. Semi-analytical expressions for the,escape times are derived. Calculations are compared to experimental results and previous numerical simulations. Significant correlations between the Position,of quantum-well energy levels and the value of the escape time are found. the main escape mechanism At room temperature is established to be thermally assisted tunneling/emission through near-barrier-edge states. The formation of a new eigenstate in the near-barrier-edge energy region is found to reduce the electron escape time significantly, which can be used for practical device optimization

Excitonic Mott transition in double quantum wells

We consider an electron-hole system in double quantum wells theoretically. We demonstrate that there is a temperature interval over which an abrupt jump in the value of the ionization degree occurs with an increase of the carrier density or temperature. The opposite effect - the collapse of the ionized electron-hole plasma into an insulating exciton system - should occur at lower densities. In addition, we predict that under certain conditions there will be a sharp decrease of the ionization degree with increasing temperature - the anomalous Mott transition. We discuss how these effects could be observed experimentally.Comment: 6 pages, 4 figure

Quantum-well design for monolithic optical devices with gain and saturable absorber sections

We propose a new design of semiconductor quantum-well heterostructures, which can be used to improve the performance of monolithic mode-locked diode lasers and all-optical signal-processing devices with gain and saturable absorber sections. Numerical modeling shows that this design can increase the carrier sweep-out rate from the absorber section by several orders of magnitude, while retaining high carrier confinement on the ground level making for efficient signal amplification by the gain sections