Theory of transient spectroscopy of multiple quantum well structures

A theory of the transient spectroscopy of quantum well (QW) structures unde r a large applied bias is presented. An analytical model of the initial par t of the transient current is proposed. The time constant of the transient current depends not only on the emission rate from the QWs, as is usually a ssumed, but also on the subsequent carrier transport across QWs. Numerical simulation was used to confirm the validity of the proposed model, and to s tudy the transient current on a larger time scale. It is shown that the tra nsient current is influenced by the nonuniform distribution of the electric field and related effects, which results in a step-like behavior of the cu rrent. A procedure of extraction of the QW emission time from the transient spectroscopy experiments is suggested. (C) 1999 American Institute of Phys ics. [S0021-8979(99)00315-1].