Spectral hole-burning in quantum confined semiconductor microcrystals

Ultrafast dynamics of carrier-induced absorption changes in highly-excited CdSe nanocrystals

“…It has been found that semiconductor crystallites with radii on the order of a few nanometer, denoted as nanocrystals (NCs), can be rather easily produced in semiconductor-doped glasses (which are commercially available as color-glass filters) or in organic solution [2][3][4]. The linear absorption of such samples generally shows a correlation with the average NC size, as the lowest absorption feature shifts towards higher energies with decreasing size [3,[5][6][7][8][9][10][11]. While this clear sign of size quantization is easily observed, the absorption spectra of semiconductordoped glasses usually fail to show sharp exciton peaks (in contrast with two-dimensional quantum wells) or even wellseparated absorption lines that reflect the expected discrete energy spectrum of a "zero-dimensional" structure.…”

“…The linear absorption of such samples generally shows a correlation with the average NC size, as the lowest absorption feature shifts towards higher energies with decreasing size [3,[5][6][7][8][9][10][11]. While this clear sign of size quantization is easily observed, the absorption spectra of semiconductordoped glasses usually fail to show sharp exciton peaks (in contrast with two-dimensional quantum wells) or even wellseparated absorption lines that reflect the expected discrete energy spectrum of a "zero-dimensional" structure.…”

“…A large amount of experimental and theoretical work has been done to determine the absorption and luminescence properties of semiconductor NCs and to gain insight in their energy structure and dominant broadening mechanisms [3,[7][8][9][10][11]13]. The magnitude and the dynamics of the optical nonlinearities have been investigated with various experimental techniques, such as single-beam absorption saturation, [15] pump-probe measurements in the nanosecond, [4,6,7,9,10,16] picosecond, [5,17,18] and femtosecond regime, [4,19] and photon-echo experiments [11,14,20].…”

“…The magnitude and the dynamics of the optical nonlinearities have been investigated with various experimental techniques, such as single-beam absorption saturation, [15] pump-probe measurements in the nanosecond, [4,6,7,9,10,16] picosecond, [5,17,18] and femtosecond regime, [4,19] and photon-echo experiments [11,14,20].…”

“…This value may be reduced to a few percent by sophisticated preparation techniques, but even then the size distribution has a significant influence on the optical properties [4,10,13]. In addition, electron-phonon coupling and the large number of "dangling bonds" at the surface of the NCs may lead to a considerable homogeneous broadening that is at least comparable to the inhomogeneous broadening at room temperature [5,14].A large amount of experimental and theoretical work has been done to determine the absorption and luminescence properties of semiconductor NCs and to gain insight in their energy structure and dominant broadening mechanisms [3,[7][8][9][10][11]13]. The magnitude and the dynamics of the optical nonlinearities have been investigated with various experimental techniques, such as single-beam absorption saturation, [15] pump-probe measurements in the nanosecond, [4,6,7,9,10,16] picosecond, [5,17,18] and femtosecond regime, [4,19] and photon-echo experiments [11,14,20].…”