Characterization of silicon nitride thin films deposited by hot-wire CVD at low gas flow rates

We examined the chemical, structural, mechanical and optical properties of amorphous hydrogenatedsilicon nitride thin films deposited by hot-wire chemical vapour deposition using SiH4, NH3and H2gases at total flow rates below 33 sccm. Time of flight secondary ion mass spectroscopy reveal that thefilm surfaces consist of predominantly Si with hydrogenated SixNyOzspecies. Energy dispersive X-rayspectroscopy and X-ray photoelectron spectroscopy corroborate on the N/Si ratio. Electron energy lossspectroscopy discloses that the thickness of the nitrogen rich oxidized interface between the SiNxfilmsand the c-Si substrate decrease with an enhancing NH3flow rate. By varying the NH3flow rate, denseSiNxfilms can be realized with hydrogen content between 16 and 9 at.%, a refractive index between 3.5and 1.9 and optical band gap ranging from 2 to 4.5 eV. The SiNxfilm stress is compressive for N/Si 0.55. Mechanisms relating the HWCVD conditions and the film structure andproperties are proposed.Web of Scienc

Controlled Deposition of Lead Iodide and Lead Chloride Thin Films by Low-Pressure Chemical Vapor Deposition

Lead halide thin films, such as lead iodide (PbI2) and lead chloride (PbCl2), are used as precursor films for perovskite preparation, which is frequently achieved by vacuum thermal evaporation but rarely by the low-pressure chemical vapor deposition (CVD) method. Here, we report on the deposition of PbI2 and PbCl2 thin films on glass substrates by employing the low-pressure CVD method. The effect of the substrate temperature on the structure and morphology of the lead halide films is investigated. Crystalline films were realized for both lead halides, with PbI2 films showing high texture compared to the reduced texture of the PbCl2 films. Large lateral grain sizes were observed for the PbI2 films with a flat platelet grain morphology and an average grain size up to 734.2 ± 144.8 nm. PbCl2 films have columnar grains with an average grain size up to 386.7 ± 119.5 nm. The PbI2 films showed a band gap of about 2.4 eV, confirming its semiconducting properties, and the PbCl2 had a wide band gap of 4.3 eV, which shows the insulating properties of this material