Efficient photoluminescence ~PL! up-conversion has been observed in colloidal CdTe quantum dots with an energy gain of as high as 360 meV. Compared with the normal PL, the peak energy of this up-converted PL ~UCPL! shows a redshift of about 80 meV, and the corresponding radiative lifetime becomes nearly twice as long. This UCPL is attributed to the carrier recombination involving surface states...

We experimentally investigate the dynamics of spins in GaAs quantum wells under applied electric bias by photoluminescence (PL) measurements excited with circularly polarized light. The bias-dependent circular polarization of PL (P(PL)) with and without magnetic field is studied. The P(PL) without magnetic field is found to be decayed with an enhancement of increasing the strength of the negati...

Integration of quasi-two-dimensional (2D) films of metal-chalcogenides in optical microcavities permits new photonic applications of these materials. Here we present tunable microcavities with monolayer MoS2 or few monolayer GaSe films. We observe significant modification of spectral and temporal properties of photoluminescence (PL): PL is emitted in spectrally narrow and wavelength-tunable cav...

We fabricated a silicon nanocrystal (NC) suspension with visible, continuous, tunable light emission with pH sensitivity from violet to blue-green. Transmission electron microscopy (TEM) images and X-ray diffraction (XRD) pattern analysis exhibit the highly crystalline nanoparticles of silicon. Photoluminescence (PL) spectra and photoluminescence excitation (PLE) spectra at different pH values,...

This work reports the coating of porous silicon (PS) with LaF3 and its influence on the photoluminescence (PL) property of PS. PS samples, prepared by electrochemical etching in a solution of HF and ethanol, were coated with e-beam evaporated-LaF3 of different thicknesses. It was observed that the thin LaF3 layer on PS led to a good enhancement of PL yield of PS. But with the increasing thickne...

The luminescence of amorphous silicon layers either implanted with Er or co-implanted with Er and O has been studied by photoluminescence (PL) and cathodoluminescence (CL) in the scanning electron microscope. Annealing in nitrogen causes the formation of oxide species and Er-Si complexes or precipitates as well as spectral changes in the visible and infrared ranges. The main CL emission takes p...

We report photoluminescence (PL) studies of high-quality Zn 1~x Be x Se "lms grown by molecular beam epitaxy (MBE) on GaAs substrates by use of a novel growth method of Be}Zn co-irradiation before the growth of a thin ZnSe bu!er layer. Samples show double-crystal X-ray linewidth as narrow as 23 arcsec. Low-temperature (13K) PL of undoped samples showed free exciton emission, which de"ned the ba...

Self-assembled InAs bi-quantum-dot molecules (BQDMs) on GaAs (0 0 1) have been achieved using gas-source molecular beam epitaxy (GSMBE) and characterized by atomic force microscopy (AFM) and photoluminescence (PL) measurements. After the initial InAs quantum dots are partially capped with GaAs and followed by deposition of InAs, BQDMs are formed. Photoluminescence spectra of BQDMs can be descri...

We studied the temperature and excitation intensity dependence of exciton luminescence in individual single-walled carbon nanotubes (SWNTs) using single nanotube photoluminescence (PL) spectroscopy. The linear temperature dependence of the PL linewidth in a single SWNT implies that the exciton dephasing is dominated by the interaction between the exciton and the phonon mode with very low energy...

Growing high quality monolayer MoS2 with strong photoluminescence (PL) is essential to produce light-emitting devices on the atomic scale. In this study we show that rhombic monolayer MoS2 with PL intensity 8 times stronger than those of chemical vapour deposition (CVD)-grown triangular and mechanically exfoliated (ME) monolayer MoS2 can be prepared by using CVD. Both Raman and PL measurements ...