Incoherent Photon Echo in an Inhomogeneous Ensemble of Semiconductor Colloidal Quantum Dots at Low Temperatures

A simple and effective technique for fabricating homogeneous films of colloidal quantum dots is developed. Incoherent photon echo signals in the prepared thin films of quantum dots are detected and studied in a wide range of cryogenic temperatures (from 4.5 to 50 K). The temperature dependence of the inverse optical dephasing time is constructed and possible mechanisms of ultrafast dephasing are analyzed in the indicated temperature range.