Moisture barrier enhancement by spontaneous formation of silicon oxide interlayers in hot wire chemical vapor deposition of silicon nitride on poly (glycidyl methacrylate)

We deposited a silicon nitride (SiNx)–polymer hybrid multilayer moisture barrier in a hot wire chemical vapor deposition (HWCVD) process, entirely below 100 °C. The polymer, poly(glycidyl methacrylate) (PGMA), was deposited by initiated chemical vapour deposition and the SiNx in a dedicated HWCVD reactor. Line profile investigation of our barrier structures by cross-sectional scanning transmission electron microscopy and energy dispersive X-ray spectrometry reveals that, upon deposition of SiNx on top of our polymer layer, an intermediate layer of silicon oxide (SiOx) like material is formed. X-ray photoelectron spectroscopy measurements confirm the presence of this material and indicate the epoxy rings in the PGMA material open upon heating (to 100 °C) and exposure to atomic hydrogen and amine species in the HWCVD process. The oxygen atoms subsequently react with silicon and nitrogen containing radicals to form SiOxNy. The interlayer turns out to be highly beneficial for interlayer adhesion and this is considered to be one of the reasons for the excellent barrier properties of our multilayer

Shutterless deposition of phosphorous doped microcrystalline silicon by Cat-CVD

In this paper we present results on phosphorous-doped μc-Si:H by catalytic chemical vapour deposition in a reactor with an internal arrangement that does not include a shutter. An incubation phase of around 20 nm seems to be the result of the uncontrolled conditions that take place during the first stages of deposition. The optimal deposition conditions found lead to a material with a dark conductivity of 12.8 S/cm, an activation energy of 0.026 eV and a crystalline fraction of 0.86. These values make the layers suitable to be implemented in solar cells

Thinner silicon-based tandem solar cell with high efficiency made by hot wire CVD

We developed thin film silicon tandem cells with hot-wire deposited amorphous (protocrystalline) and nanocrystalline i-layers, with a total thickness of only 1.43 µm. This is considerably thinner than the thickness of 2.5–3.0 µm normally needed, which is important to significantly reduce production costs for this type of cells. An initial efficiency of 8.84% was obtained. The top cell is ∼220 nm and the bottom cell only ∼1210 nm thick. No intermediate reflector layer is introduced. Compared to standard PECVD tandem cells, the Voc is remarkably high, consistent with the beneficial effect of thin i-layers on Voc and with the high Voc of 0.57 V obtained for single junction HWCVD nc-Si:H cells. After over 2000 hours of light soaking, a stabilized efficiency of 7.63% was obtaine

Optoelectronic properties of hot-wire silicon layers deposited at 100 °C

Hot-wire chemical vapor deposition is employed for the deposition of amorphous and microcrystalline silicon layers at substrate temperature kept below 100 °C with the aid of active cooling of the substrate holder. The hydrogen dilution is varied in order to investigate films at the amorphous-to-microcrystalline transition. While the amorphous layers can be produced with a reasonably low defect density as deduced from subgap optical absorption spectra and a good photosensitivity, the microcrystalline layers are of a lesser quality, most probably due to a decrease of crystallinity during the film growth. In the amorphous growth regime, the Urbach energy values decrease with increasing hydrogen dilution, reaching a minimum of 67 meV just before the microcrystalline threshold. By varying the total gas pressure, the growth rate of the films is changed. The lowest deposition rate of this study (0.16 nm/s) produced the amorphous sample with the highest photoresponse (1 × 106)

Moisture barrier enhancement by spontaneous formation of silicon oxide interlayers in hot wire chemical vapor deposition of silicon nitride on poly (glycidyl methacrylate)

We deposited a silicon nitride (SiNx)–polymer hybrid multilayer moisture barrier in a hot wire chemical vapor deposition (HWCVD) process, entirely below 100 °C. The polymer, poly(glycidyl methacrylate) (PGMA), was deposited by initiated chemical vapour deposition and the SiNx in a dedicated HWCVD reactor. Line profile investigation of our barrier structures by cross-sectional scanning transmission electron microscopy and energy dispersive X-ray spectrometry reveals that, upon deposition of SiNx on top of our polymer layer, an intermediate layer of silicon oxide (SiOx) like material is formed. X-ray photoelectron spectroscopy measurements confirm the presence of this material and indicate the epoxy rings in the PGMA material open upon heating (to 100 °C) and exposure to atomic hydrogen and amine species in the HWCVD process. The oxygen atoms subsequently react with silicon and nitrogen containing radicals to form SiOxNy. The interlayer turns out to be highly beneficial for interlayer adhesion and this is considered to be one of the reasons for the excellent barrier properties of our multilayer

Nanorod solar cell with an ultrathin a-Si:H absorber layer

We propose a nanostructured three-dimensional (nano-3D) solar cell design employing an ultrathin hydrogenated amorphous silicon (a-Si:H) n-i-p junction deposited on zinc oxide (ZnO) nanorod arrays. The ZnO nanorods were prepared by aqueous chemical growth at 80 °C. The photovoltaic performance of the nanorod/a-Si:H solar cell with an ultrathin absorber layer of only 25 nm is experimentally demonstrated. An efficiency of 3.6% and a short-circuit current density of 8.3 mA/cm2 were obtained, significantly higher than values achieved for planar or even textured counterparts with three times thicker ( ∼ 75 nm) a-Si:H absorber layers

Low Temperature Silicon Nitride by Hot Wire Chemical Vapour Deposition for the Use in Impermeable Thin Film Encapsulation on Flexible Substrates

High quality non porous silicon nitride layers were deposited by hot wire chemical vapour deposition at substrate temperatures lower than 110 C. The layer properties were investigated using FTIR, reflection/transmission measurements and 1:6 buffered HF etching rate. A Si–H peak position of 2180 cm−1 in the Fourier transform infrared absorption spectrum indicates a N/Si ratio around 1.2. Together with a refractive index of 1.97 at a wavelength of 632 nm and an extinction coefficient of 0.002 at 400 nm, this suggests that a transparent high density silicon nitride material has been made below 110 C, which is compatible with polymer films and is expected to have a high impermeability. To confirm the compatibility with polymer films a silicon nitride layer was deposited on poly(glycidyl methacrylate) made by initiated chemical vapour deposition, resulting in a highly transparent double layer