Exciton Luminescence of CuCl Associated with a New Bound State Generated by Long Time Photo-irradiation

Optical fabrication of wide‐gap semiconductor nanoparticles in superfluid helium

“…It is found that the electron beam excitation attended by the injection of electrons can improve the luminescence efficiency in CuCl. These features and the peak energies are in agreement with those of the bound exciton bands generated by long time photo-irradiation [23,24]. After stopping the irradiation of electron beam for an hour, these bands in CL appear instantaneously by resuming the irradiation.…”

Morphology changes of CuCl thin films induced by photo‐irradiation

“…We assume that all the energy of the single laser pulse is immediately converted to heat in a disc, the diameter and the thickness of which are 200 µm and 50 nm, respectively. The expected increase in the disc temperature is approximately 0.05 K. The result is consistent with the fact that we detect no energy shift of the exciton luminescence when we change the excitation light intensity because the energy position of the exciton luminescence works as a thermometer of the sample [8]. Thus, the heating effect is confirmed to be negligible.…”

“…. Characteristics of the films are determined by the growth conditions, such as a substrate surface, a substrate temperature and a growth speed, and have been thought to be free from effects of photoirradiation for the photo-luminescence observation.Recently, we found that a decrease in the exciton luminescence intensity and appearance of new bound exciton luminescence of CuCl bulk and vapor-evaporated films on TiO 2 , Al 2 O 3 and synthesized quartz were induced by photo-irradiation with ultra-violet light pulses at 4.6 K [7,8]. In the series of the experiments we recognized the photo-irradiated spot in thin films by eye after the photo-irradiation.…”

“…A possible candidate to the bound state is a Cu + vacancy [11]. The luminescence A and B are the emission of another bound state of the Z 3 excitons generated by the photo-irradiation, the origin of which is not clear at present [8]. In a few minutes of photoirradiation, the intensities of the Z 3 exciton and I 1 luminescence decrease.…”

“…The temporal change of the exciton luminescence spectrum is shown in Refs. [7] and [8]. Figure 2 shows an optical microscope image of the 50 nm thick CuCl film after 10 h of photoirradiation at 4.6 K. The image is obtained at room temperature.…”