Ultrafast carrier transport and capture in InGaAs/InP heterostructures

The carrier dynamics in InGaAs/InP heterostructures is studied with luminescence up-conversion spectroscopy with 300 fs time resolution. A comparative study using samples with different well and barrier thicknesses is performed to separate the carrier transport across the InP barriers to the quantum wells (QWs) and the final carrier capture into confined states of the quantum wells. Samples with different Ga-content of the InGaAs QW layers are also investigated. The capture times are virtually independent of well width. Local capture time constants of about 800 fs for electrons and 200 fs for holes are determined by model calculations. It is concluded that the modulation frequency of devices up to 300 GHz is not limited by the charge transfer from barriers to wells.<>