Many experiments have reported that the siliconrich silicon nitride thin films can emit strong visible light at room temperature

at light excitation

and the silicon-rich silicon nitride thin films were usually prepared through plasma enhanced chemical vapor deposition (PECVD) technology or low pressure chemical (vapor) deposition (LPCVD) technology

among which the thin films made by PECVD technology was used and researched more often

for the lower temperature. Yet the silicon nitride thin films obtained by LPCVD have many advantages than the silicon nitride thin films by PECVD

including higher refractive index

higher den-(sity

) higher resistivity

higher breakdown field

higher band gap and so on. Moreover

although experiments concluded all the silicon nitride thin films showing photoluminescence have mosaic structure of silicon nano-dots embedded in amorphous silicon nitride films

the size and the number of silicon nano-dots is quite diffe-(rent) in the films made by LPCVD and PECVD

which means they may have different luminescence mechanics. So our team has researched the photoluminescence mechanics of silicon nitride films prepared by LPCVD in the last year. By choosing different deposition condition during the samples preparing

the microstructure and the defects of the thin films can be changed

as a result

the PL spectrum will change consequentially. Using TEM

IR and XPS

the luminescence mechanics of the silicon nitride thin films were investigated. We changed the ratio of dichlorosilane to ammonia

keeping the deposition temperature at 900℃. The result shows quite different PL spectra

and we has explained the results using our gap states (model.)