STATE FILLING, COULOMB, AND TRAPPING EFFECTS IN THE OPTICAL NONLINEARITY OF CDTE QUANTUM DOTS IN GLASS

Microcrystallites of CdTe were grown in a special-formula glass, yielding CdTe dots; the linear-absorption spectrum exhibits as many as six quantum-confinement peaks. Excitation of the sample with pulses ranging from femtoseconds to microseconds has allowed us to distinguish between various mechanisms for optical nonlinearity. At very early times, phase-space filling and Coulomb interaction between the excited charged carriers is responsible for the absorption changes, ±. At later times, Coulomb effects due to trapped carriers remain and last for nanoseconds or microseconds. © 1990 The American Physical Society.