The Study of p,n Control of room-temparature Photoluminescence Thin Films

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Digital Kelvin prove was purchased and the system was attached to our UHV system. The system worked to measure work functions of the samples prepared with pulsed laser deposition. Work functions of the prepared samples can be measured by the charge difference between the probe tip and the sample so called CPD value indirectly. The system needed standard samples, for instance, Au,Ag,and Si whose work functions have been known and their CPD values have to be measured as a function of their work functions. It was found that doped ions in CdWO4 single crystals played significant roles on the charge distribution on their surfaces and therefore unexpectedly large work function values were apparently estimated. Only few results have been reported with digital Kelvin prove so that it is required to distinguish whether the system is measurement possible or not. It should be also considered that large surface area of the probe demands the heterogeneity of the sample surface.In this system, we co … More uld measure the work function measurement on the K/O/Si nanoparticles. It is reported that work function drastically decreases in the system of alkaline/oxygen/Silicon mixture because of negative electron affinity(NEA). So far the smallest work function value of 0.8eV has been reported, however, we could obtain 0.7eV in the K/O/Si nanoparticles. We are expecting that the system could work as one of cold emission materials.Some papers have been published. Ion-doped CdWO4 thin films have been successfully prepared and their PL intensities were drastically enhanced. The effect of laser fluence on the termination of Si species prepared with pulsed laser ablation was reported. The Si species could be encapsulated in zeolite supercages and showed specific PL. The time resolved PL spectra were studied on this system and it was found that Si species encapsulated in zeolite pores shows very short nanoseconds decay time which is quite significant in this system. The discrimination of p-type or n-type is designed to these interesting materials with the present digital Kelvin probe system. Less