A simple and efficient approach was presented to enhance up-conversion emissions significantly for the Er:Al2O3 nanocrystals by Mo support (Er-Mo:Al2O3) with a 976 nm laser diode excitation. Mo support had evident effects on the phase structure and up-conversion emissions for the Er:Al2O3 nanocrystals, which promoted the -(Al,Er)2O3 transformed to -(Al,Er,Mo)2O3 phase. Compared with the Er:Al2O3, the maximal green and red up-conversion emissions intensities increased about 3×103 and 1.4×102 times for the Er-Mo:Al2O3 nanocrystals, respectively. It suggests that the enhancement of up-conversion emissions is caused by the high excited state energy transfer process from |4I15/2, 3T2> state of the Er3+-MoO42 dimer to the 4F7/2 level of Er3+.
Hydrogenated microcrystalline silicon(c-Si:H) thin films were deposited by inductively coupled plasma assistant magnetron sputtering(ICP-MS) in an Ar-H 2 gas mixture.The role of ion bombardment in the growth of c-Si:H films was studied with increasing negative bias voltages on the substrate holder from 0 to 100 V.Raman scattering,X-ray diffraction(XRD),Fourier transform infrared(FTIR) spectroscopy and transmission electron microscopy(TEM) were performed to investigate the microstructure changes of deposited Si films.Raman scattering showed that the high energy ion bombardment resulted in crystalline degradation of Si films.The XRD results showed the decrease and even elimination of preferential growth orientation of crystalline Si films with ion bombardment energy increase.The SiH bonding configuration changes and the increase of bonded hydrogen concentration were determined with the analysis of FTIR spectra.Furthermore,the dramatic evolution of cross-sectional morphology of Si thin films was detected by TEM observation.
