Persistent spectral-hole-burning in semiconductor quantum dots and its application to spectroscopy

Persistent spectral-hole-burning (PSHB) phenomena have been observed in man y kinds of semiconductor quantum dots (QDs). Luminescence hole burning and charged excitons have been observed in CuCl QDs in NaCl crystals. The obser ved PSHB phenomena are explained by the ionization of QDs. The energy of ph otoionized QDs is changed from the original energy and their new energies d epend on the spatial arrangement of trapped carriers. Quantum confinement o f carriers and the resulting strong Coulomb interaction between confined ca rriers and trapped carriers cause the energy change. PSHB has been widely a pplied to site-selective spectroscopy of QDs. Size-dependent excited excito n quantum states in CuCl quantum cubes, size-dependent excited electron-hol e quantum states in CdTe QDs and renormalization of longitudinal optical ph onons confined in CuCl QDs have been revealed by studying sideband holes. T his also allowed the measurement of accumulated photon echo, which clarifie d the very sharp homogeneous spectral linewidth of QDs under weak excitatio n conditions.