Microcrystalline silicon thin films prepared by the layer-by-layer technique in a standard radio-frequency glow discharge reactor were used as the active layer of top-gate thin-film transistors (TFTs). Crystalline fractions above 90% were achieved for silicon films as thin as 40 nm and resulted in TFTs with smaller threshold voltages than amorphous silicon TFTs, but similar field effect mobilities of around 0.6 cm²/V s. The most striking property of these microcrystalline silicon transistors was their high electrical stability when submitted to bias-stress tests. We suggest that the excellent stability of these TFTs, prepared in a conventional plasma reactor, is due to the stability of the $\mathrm{\mu c-}\mathrm{Si:H}$ films. These TFTs can be used in applications that require high stability for which $\mathrm{a-}\mathrm{Si:H}$ TFTs cannot be used, such as multiplexed row and column drivers in flat-panel display applications, and active matrix addressing of polymer light-emitting diodes.

The feasibility of metrological characterization of the one-dimensional (1D) holographic gratings, used in the nanoimprint molding tool fabrication step, by spectroscopic Mueller polarimetry in conical diffraction is investigated. The studied samples correspond to two different steps of the replicated diffraction grating fabrication process. We characterized master gratings that consist of patterned resist layer on chromium-covered glass substrate and complementary (replica) gratings made of nickel. The profiles of the gratings obtained by fitting the experimental spectra of Mueller matrix coefficients taken at different azimuthal angles were confirmed by atomic force microscopy (AFM) measurements. The calculated profiles of corresponding master and replica gratings are found to be complementary. We conclude that the Mueller polarimetry, as a fast and non-contact optical characterization technique, can provide the basis for the metrology of the molding tool fabrication step in the nanoimprint technique.

In the field of plasma deposition of amorphous and microcrystalline silicon, the increase of the excitation frequency has often been considered as a way to enhance the deposition rate. Moreover, the increase of pressure has also been shown to enhance the deposition rate and improve the film properties. We attempt to clarify the effects of frequency in the 13.56–40.68 MHz range and to compare them to those of the pressure in the range of 0.5–1.5 Torr. For that purpose we use a numerical modeling of capacitively coupled hydrogen plasma, particularly relevant for the deposition of microcrystalline silicon. We use a one-dimensional time-dependent fluid model for the description of neutrals, positive and negative ions, and electrons, which involves a chemistry model taking into account 32 reactions in the gas phase and on the surface of the electrodes. The results of the model for the symmetrical system show that both pressure and frequency have pronounced influence on the parameters of the discharge: sheath thickness, ratio between power transferred to ions and electrons, and concentration and flux of atomic hydrogen at the electrode surface. We found that increasing the excitation frequency, while keeping constant the power dissipated in the plasma, leads to a more moderate increase of electron density as compared with the case of constant rf-voltage amplitude. The analysis of this phenomenon reveals that, with increase of frequency, the power coupling to the electrons becomes more efficient due to the decrease of the phase shift between voltage and current for both constant power and constant voltage conditions. There is, in addition, a significant drop of the sheath voltage with frequency when the power dissipated in the plasma is kept constant. This leads to the reduction in the drift loss rate for charged species. The increase of pressure mainly reduces the diffusive component of the loss rate for both charged and neutral species and, as a result, electron density enhancement is less pronounced. The increase of pressure leads to a more uniform spatial dissipation of the power coupled to the plasma, whereas the increase in frequency results in a higher amount of power dissipated on the plasma-sheath boundaries due to the decrease of the sheath width.

The deposition of silicon alloys for protective and optical coatings on polymers is of increasing interest. The understanding of the plasma polymer interaction is of prime importance here. In this work, we report a study of the influence of N2, H2, and O2 plasma treatments on pure and commercial grade polycarbonate (PC) in order to enhance the adhesion of plasma deposited silica films. Treatments and depositions were carried out in a low pressure (1 mTorr range) integrated distributed 2.45 GHz microwave electron cyclotron resonance reactor, which allows the deposition of dense stoechiometric silica at room temperature. The plasma–polymer interaction is studied by in situ UV-visible spectroscopic ellipsometry on thin spin-coated PC films. The absorption in the PC layer was found to increase in the UV which was attributed to the different reaction products of photo-Fries rearrangements, especially for pure PC. Gel permeation chromatography measurements showed that the major influence of plasma treatment on pure polycarbonate is chain scission opposed to crosslinking in the case of commercial grade PC, indicating that additives present in commercial grade PC play a major role in the crosslinking mechanisms. The plasma treatment modifies the top 330 nm/homogeneously and no indication of a high index surface layer (50–200 nm) or gradient was found. This is attributed to the low pressure of the plasma treatment, which makes a redeposition of volatile organic species unlikely.