Semiconductor nanoclusters luminescence

Surface plays an important role in excited state relaxation processes. In the ideal case of a three-dimensionally confined exciton, one expects to see strong exciton luminescence due to enhanced overlap of the electron and hole wavefunction. The radiative rate of the exciton should increase with increasing cluster size. In reality, this is generally not observed. Most of the luminescence spectra of semiconductor nanoclusters consist of a stokes-shifted broad luminescence band, usually attributed to emission from surface defects. Sometimes near the band edge, an exciton-like luminescence band can be observed. Various passivation procedures have been used to enhance the exciton luminescence. These are discussed in Section III. 

---