Boron-doped Films Research Articles

Boron-doped carbon nano dot anchored thin film coating on cobalt vanadium oxide for ultrafast energy storage devices

Lithium-ion capacitors (LICs) with ultrafast rate capabilities are required to increase the applicability of rechargeable energy storage devices. Considering that the power density of an LIC is primarily determined by the anode properties, carbon coating onto the anode material is a promising method of accelerating electron transfer between particles and alleviating structural collapse during repeated charge–discharge cycles. In this study, a new coating configuration featuring a boron-doped carbon nano dot-anchored thin film on cobalt vanadium oxide (BC-CVO) was demonstrated. The coating morphology, wherein the carbon nano dots were connected by a thin carbon film, induced nano-scale surface roughness on CVO, expanding the contact area between the functional groups on the coating layer and electrolyte. The boron-doped carbon lattice structure provided ultrafast electron transfer inside the CVO particles, which allowed reversible electron transfer even under ultrafast charge–discharge cycles. This morphological and chemical combination significantly improved the ultrafast-rate capability of the LIC anodes (429.6 mAh/g at 4000 mA/g and 534.3 mAh/g after 1000 cycles at 2000 mAh/g) compared to that of bare CVO. Furthermore, an LIC full cell fabricated with a BC-CVO anode and an activated carbon cathode showed high energy and power densities.

Novel approach to produce 3D boron-doped diamond for pollutant removal from water

Diamond growth from Chemical Vapor Deposition (CVD) on foreign substrates can require different pretreatment not only to improve the film nucleation but also to assure its adhesion by decreasing the expected film/substrate interface stress. To improve boron-doped film nucleation, growth, and adherence, different substrate pretreatments have been used mainly from the seeding process with diamond powder at various particle sizes. Despite this, the development of diamond growth on a Ti mesh remains difficult because of the requirement of a cohesive film to cover a 3D macroporous sample with varying growth rates based on its distinct network geometry. Then, this work describes a novel approach to growing boron-doped diamond (BDD) and boron-doped ultrananocrystalline diamond (B-UNCD) on titanium dioxide nanotubes (TDNT) produced simultaneously on both sides of Ti mesh by an anodization process. The films were obtained from two-step growth processes by assuring the entire diamond overlay on both TDNT/Ti mesh sides, including their outer/inner surfaces, as a 3D sample. TiO2 - TiC conversion has dominated the renucleation process, facilitating the nanometric scale control. The film morphologies were systematically analyzed by FEG-SEM images at different sample planes and depths for both sample sides at different stages of film growth. The unique morphology of titania nanotubes associated with columnar and/or renucleation development of BDD, considering the film defects and valley, can systematically increase the electrode specific area. Raman spectra showed the film quality and its micro and/or ultrananodiamond structure and the boron doping features. Also, this growth process allowed a dopant-controlled adjustable conductivity. Then, the boron doping levels for both films were evaluated from Mott-Schottky plots at around 1019 Bcm−3, characterizing them with good conductivity. In addition, electrochemical measurements from Cyclic Voltammetry (CV) confirmed the expected diamond response on redox pair following the quasi-reversible criteria as high-performance diamond electrodes and in situ Raman spectroelectrochemical measurements assessed the stability of samples during electrochemical measurements, ensuring structural integrity. Finally, the samples were applied to the degradation of methylene blue, proving to be superior materials for electrochemical applications due to their advantages compared to those of similar 2D electrodes.

Low-thermal-budget electrically active thick polysilicon for CMOS-First MEMS-last integration

Low-thermal-budget, electrically active, and thick polysilicon films are necessary for building a microelectromechanical system (MEMS) on top of a complementary metal oxide semiconductor (CMOS). However, the formation of these polysilicon films is a challenge in this field. Herein, for the first time, the development of in situ phosphorus-doped silicon films deposited under ultrahigh-vacuum conditions (~10−9 Torr) using electron-beam evaporation (UHVEE) is reported. This process results in electrically active, fully crystallized, low-stress, smooth, and thick polysilicon films with low thermal budgets. The crystallographic, mechanical, and electrical properties of phosphorus-doped UHVEE polysilicon films are studied. These films are compared with intrinsic and boron-doped UHVEE silicon films. Raman spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM) and atomic force microscopy (AFM) are used for crystallographic and surface morphological investigations. Wafer curvature, cantilever deflection profile and resonance frequency measurements are employed to study the mechanical properties of the specimens. Moreover, resistivity measurements are conducted to investigate the electrical properties of the films. Highly vertical, high-aspect-ratio micromachining of UHVEE polysilicon has been developed. A comb-drive structure is designed, simulated, fabricated, and characterized as an actuator and inertial sensor comprising 20-μm-thick in situ phosphorus-doped UHVEE films at a temperature less than 500 °C. The results demonstrate for the first time that UHVEE polysilicon uniquely allows the realization of mechanically and electrically functional MEMS devices with low thermal budgets.

Growth of boron-doped diamond-like carbon films from a low-pressure high-density plasma in inductively coupled chemical vapour deposition

The main objective of this work was the preparation and optimization of boron-doped diamond-like carbon (DLC) films having a good crystalline structure, and electronic and optical properties, at an extremely low deposition pressure and relatively low growth temperature, by varying the flow rates of precursor gases (CH4, B2H6, and Ar) in the plasma controlled at 800 W of RF power. Planar inductively coupled plasma-enhanced chemical vapour deposition technique was used to enable deposition at ∼5.33 Pa and 450 °C, at a constant negative substrate bias of -40 V. The flow rate of the dopant gas (B2H6) was changed to obtain a set of samples, while the precursor gas (CH4) flow rate was kept fixed. The doped sample, prepared with B2H6/CH4 ratio (r) = 1 %, was found to possess a maximum ID/IG (intensity ratio of the D peak with the G peak) of ∼0.819 and a minimum IDia/IG ratio (relative intensity of the Diamond peak to the G peak) of ∼1.149. A high sp3 content of ∼50 % was revealed from the X-ray photoelectron spectroscopy analysis and the transmission electron microscopy images also indicated the presence of prominent 〈111〉, 〈220〉, and 〈311〉 crystallographic planes. The B-doped DLC film possessed enhanced electrical conductivity (σRT) of ∼3.02 ×10−5 S cm−1 relative to the intrinsic DLC films, a corresponding minimum of activation energy (ΔEH) (as calculated in the above room-temperature regime) of ∼170 meV, an optical band gap (Eg) of ∼3.35 eV, and the root mean square roughness of ∼48.12 nm.

Boron-Doped Thin Films Fabricated by the Spin Coating Method: The Effect of Doping Concentrations

This work examined the impact of different levels of B-doping on the structural, morphological, optical, and electrical characteristics of ZnO thin films. Boron-doped zinc oxide thin films were deposited on glass substrates using the spin-coating technique. The B concentrations employed were 1, 2, 3, 4, and 5 at. %. The systematic characterizations manifest that the properties of the deposited films were heavily influenced by changing concentrations of B doping. It was found that as the concentration of B-doping increases, the values of grain size decrease. In addition, it was observed that ZnO thin films containing a lower concentration of B dopant exhibited higher transparency. Finally, it was figured out that the resistivity of the films declines dramatically with a higher content of B-doping. The results of our research may initiate further inquiries into the creation of superior thin films.

Preparation of boron-doped diamond-like carbon films via enhanced-PECVD using an additional cathode

Boron-doped Diamond-Like Carbon (B:DLC) films with different concentrations of boron were produced in an Enhanced-PECVD reactor using trimethylborate (TMB) vapor as the boron source. An additional cathode system was incorporated inside the reactor to confine the plasma to grow B:DLC film on polished Ti-6Al-4 V and Silicon samples. The boron-containing coatings were evaluated and compared to a boron-free coating through several characterization techniques. Raman spectroscopy, Nano-hardness, XPS, RBS, and SEM techniques were employed to study the microstructure, hardness, chemical composition and bonding state, and morphology of the samples. Ball-on-disc tests were also conducted, using a tribometer to measure the friction coefficient and wear resistance. Boron was confirmed in the DLC film structure by XPS and RBS analyses. The XPS measurements showed that the boron bonding was accompanied by a higher content oxygen than carbon content, which increased with the TMB concentration. The sp3 content was evaluated, and the result showed a decrease of about 30 % with the higher solution concentration. As a consequence, the friction coefficient, wear, and hardness were affected. However, the adherence of the films was not compromised. Finally, our study indicated that the PECVD deposition system employing an additional cathode was suitable for the incorporation of boron into DLC films.

The electronic properties of boron-doped germanium nanocrystals films

Various doping concentrations of boron (B)-doped germanium nanocrystal (Ge NC) films were prepared using the plasma-enhanced chemical vapor deposition (PECVD) technique followed by thermal annealing treatment. The electronic properties of B-doped Ge NCs films combined with the microstructural characterization were investigated. It is worthwhile mentioning that the Hall mobilities {mu }_{mathrm{Hall}} of Ge NCs films were enhanced after B doping and reached to the maximum of 200 cm2 V−1, which could be ascribed to the reduction in surface defects states in the B-doped films. It is also important to highlight that the temperature-dependent mobilities {mu }_{mathrm{H}}(T) exhibited different temperature dependence trends in the Ge NCs films before and after B doping. A comprehensive investigation was conducted to examine the distinct carrier transport properties in B-doped Ge NC films, and a detailed discussion was presented, focusing on the scattering mechanisms involved in the transport process.

Excellent surface passivation of p-type TOPCon enabled by ozone-gas oxidation with a single-sided saturation current density of ∼ 4.5 fA/cm2

High-quality p-type tunnel oxide passivated contact (p-type TOPCon) is a feasible technical solution to further improve the efficiency of TOPCon silicon solar cells. Plasma-enhanced chemical vapor deposition (PECVD) technology route could deposit boron-doped amorphous silicon film in-situ and thus becomes one of the most promising industry routes to prepare the TOPCon structure. However, the passivation quality of p-type TOPCon by PECVD is not satisfactory till now. In this work, we develop the high-performance p-type TOPCon technology by integrating the ozone-gas oxidation to prepare the ultra-thin SiOx film, which shows excellent passivation and contact properties. The experimental results suggest that the double-sided p-type TOPCon passivated samples with p-type Si substrates receive a maximal implied open-circuit voltage (iVoc) of ∼ 734 mV together with a minimum single-sided saturation current density (J0,s) of ∼ 4.5 fA/cm2. Correspondingly, the contact resistivity is less than 5 mΩ·cm2, yielding a high selectivity S10 of 15.6, which is one of the best values for p-type TOPCon technology. As a result, the precursor cell manifests an excellent iVoc of 717 mV, and the p-type silicon solar cell with rear-sided p-type TOPCon passivating contact receives a high efficiency of 22.23%. Generally, this work provides a promising technology for preparing the high-quality p-type TOPCon passivating contact for industrial application.

Sputtering Codeposition and Metal-Induced Crystallization to Enhance the Power Factor of Nanocrystalline Silicon.

The power factor of highly boron-doped nanocrystalline Si thin films with controlled doping concentration is investigated. We achieve a high degree of tuning of boron content with a charge carrier concentration from 1018 to 1021/cm3 and with the electrical conductivity by varying the boron magnetron power from 10 to 60 W while maintaining the power of a SiB source constant during codeposition from two independent sputtering sources. Along with the increase in the electrical conductivity with increased boron doping, we observe a steady decrease in the Seebeck coefficient from 500 to 100 μV/K. These values result in power factors that exhibit a marked maximum of 5 mW/K2m for a carrier concentration of around 1021/cm3 at room temperature. Temperature-dependent measurements up to 650 °C show, with increasing doping concentration, a change of the resistivity from a semiconducting to a metallic behavior and an increase of both Seebeck coefficient and power factor, with this last one peaking at 9.8 mW/K2m in the 350-550 °C temperature range. For higher concentrations, scanning electron microscopy and energy-dispersive X-ray spectroscopy show a partial segregation of boron on particles on the surface. These results exemplify the great advantage of sputtering codeposition methods to easily tune and optimize the thermoelectric performance in thin films, obtaining in our specific case highly competitive power factors in a simple and reliable manner.

Femtosecond Laser Fabrication of Anisotropic Structures in Phosphorus- and Boron-Doped Amorphous Silicon Films.

Femtosecond laser-modified amorphous silicon (a-Si) films with optical and electrical anisotropy have perspective polarization-sensitive applications in optics, photovoltaics, and sensors. We demonstrate the formation of one-dimensional femtosecond laser-induced periodic surface structures (LIPSS) on the surface of phosphorus- (n-a-Si) and boron-doped (p-a-Si) amorphous silicon films. The LIPSS are orthogonal to the laser polarization, and their period decreases from 1.1 ± 0.1 µm to 0.84 ± 0.07 µm for p-a-Si and from 1.06 ± 0.03 to 0.98 ± 0.01 for n-a-Si when the number of laser pulses per unit area increases from 30 to 120. Raman spectra analysis indicates nonuniform nanocrystallization of the irradiated films, with the nanocrystalline Si phase volume fraction decreasing with depth from ~80 to ~40% for p-a-Si and from ~20 to ~10% for n-a-Si. LIPSS' depolarizing effect, excessive ablation of the film between LIPSS ridges, as well as anisotropic crystalline phase distribution within the film lead to the emergence of conductivity anisotropy of up to 1 order for irradiated films. Current-voltage characteristic nonlinearity observed for modified p-a-Si samples may be associated with the presence of both the crystalline and amorphous phases, resulting in the formation of potential barriers for the in-plane carrier transport and Schottky barriers at the electric contacts.

Effects of PECVD preparation conditions and microstructures of boron-doped polysilicon films on surface passivation of p-type tunnel oxide passivated contacts

We investigate the effects of plasma-enhanced chemical vapor deposition (PECVD) preparation conditions and microstructures of the boron-doped polysilicon films on the passivation quality of p-type tunnel oxide passivated contact (p-TOPCon) integrated with plasma-assisted N2O oxidation (PANO) SiOx. The B2H6 gas flow, activation temperature, substrate temperature, H2 dilution ratio, and carbon (C)-doped polycrystalline silicon insertion layer are investigated. The best passivation based on plane-surface n-type CZ-Si lifetime sample manifests an implied open-circuit voltage (iVoc) of 706 mV, a single-sided saturation current density (J0,s) of 17.9 fA/cm2, and an effective lifetime (τeff) of 2.25 ms at 1 × 1015 cm−3, showing a slight improvement compared with the controlled sample featuring an iVoc of 703 mV. Although this passivation quality is one of the best specifications of the p-TOPCon featuring PANO SiOx so far, it is insufficient for industry application. Detailed experimental studies and a numerical simulation suggest that the passivation quality is probably weakened by the boron-induced defects located at the interfacial and beneath the SiOx, whose harmful influence is difficult to offset by the field-passivating effect. Generally, we provide new insight into the bottleneck of the p-TOPCon's passivation and then discuss the new strategies for improving the p-TOPCon's passivation in this paper.

Interstitial boron-doped nanoporous palladium film for electro-reduction of nitrogen to ammonia

Electrocatalytic nitrogen reduction to ammonia has attracted abundant research interest due to its mild operation condition and sustainable feedstock. The identification of efficient catalysts with high selectivity of nitrogen reduction is the key for the electro-synthesis of ammonia. Herein, interstitial boron-doped nanoporous palladium film is directly formed on Ni foam (nPdB/NF) via micelle-assisted reduction method using borane dimethylamine complex as reducing agents and boron dopant. The binder-free nanoporous structure provides abundant active sites and facilitated mass/charge transfer. Moreover, the introduction of interstitial boron atoms can modify the electronic structure of Pd, which can both improve the nitrogen adsorption and inhibit hydrogen evolution on nPdB/NF. As such, nPdB/NF exhibits high NH3 yield of 29.0 μg h−1 mg−1cat. and Faraday efficiency of 17.9% in 0.1 M Na2SO4, superior to that of nPd/NF (19.7 μg h−1 mg−1cat and 14.7%). This work offers an attractive method for the introduction of interstitial boron into Pd-based catalysts to improve NRR performance.

Blistering-free polycrystalline silicon carbide films for double-sided passivating contact solar cells

Polysilicon (poly-Si) passivating contacts have attracted considerable attentions in the academic community and photovoltaic industry due to their remarkable advantages of outstanding passivation quality and low contact resistivity. Plasma enhanced chemical vapor deposition (PECVD), as one of the widely adopted techniques to prepare doped poly-Si films, is usually limited by the occurrence of blistering, especially for boron-doped (B-doped) poly-Si films. In this work, we present a study of PECVD preparation of B-doped polycrystalline silicon carbide (poly-SiC x ) films with a blistering-free appearance by incorporating carbon (C) and optimizing the annealing process. It demonstrates that a thick poly-Si deposited on polished c-Si substrates with a low surface roughness tends to blister, which thus leads to a poor passivation performance. Moreover, the investigation of C content and annealing condition suggests that increasing C content or lowering incipient annealing temperature is beneficial to suppress the blistering. However, the C content needs to be well controlled to balance the passivation and contact properties, because the excessive CH 4 flow during the film deposition would degrade the contact performance with a high contact resistivity (>100 mΩ cm 2 ). Finally, the proof-of-concept devices featuring the double-sided passivating contacts (DPPCs) were fabricated with a front n-type poly-Si and rear p-type poly-SiC x , and presented an open-circuit voltage of 695 mV and an efficiency of 19.82%. The results clarify the correlation of C contents, c-Si substrate roughness and annealing process with the blistering levels and the passivation/contact properties, providing a valuable guidance for fabricating high-efficiency DPPC solar cells. • A path way to prepare blistering-free Boron-doped PECVD poly-Si films has been revealed. • A 90 nm thick PECVD prepared B-doped poly-Si film with a blistering-free appearance has been proposed. • A proof-of-concept double-sided poly-Si passivating contact solar cells with an efficiency of 19.82% has been presented.

Boron induced c-axis growth and ammonia sensing signatures of spray pyrolysis deposited ZnO thin films – Relation between crystallinity and sensing

Boron (B) doping in zinc oxide (ZnO) using spray pyrolysis has always led to deterioration of host crystal structure. Unlikely, here, we report the optimized spray pyrolysis deposition parameters for the development of c-axis oriented boron-doped ZnO thin films. As the B concentration increases from 2 to 10 mol%, the hexagonal crystal structure exhibited a highly oriented (002) plane with an increased texture co-efficient. In particular, 2 mol% B dopants promoted the growth of the (101) and (100) planes and increased the crystallite size. Tensile stress in the c-axis plane of 10 mol% B-doped ZnO films leads to the red shift in the band gap (from wide to narrow). Furthermore, 10 mol% B dopants resulted in the enhanced ammonia sensing performance at room temperature. The sensing performance of all the deposited B-doped ZnO films revealed that influence of enhanced planes of host structure energetically favoured the ammonia adsorption.

Room temperature synthesized highly conducting B-doped nanocrystalline silicon thin films on flexible polymer substrates by ICP-CVD

Boron-doped nc-Si thin films were developed on inexpensive, optically-transparent, and flexible PET-substrates at ambient-temperature (∼30 °C) using (SiH4 + B2H6)-plasma, without additional H2-dilution, by optimizing the gas pressure in inductively-coupled low-pressure plasma-CVD. An amorphous and monohydride-Si dominated partially-nanocrystalline network was obtained at pressure, p ≤ 15 mTorr. At higher pressure, the local plasma heating on the polymer-substrate by the high-density plasma-precursors and over-abundant atomic-H causes plasma-induced nano-bends, which trigger the stress-induced-crystallization of the network on the flexible substrate even at ambient-temperature. Although, the enhanced atomic-H reactivity on the growing-surface at very-high pressures causes the formation of the polyhydride-dominated defective grain-boundary, which acts as the electron-trapping-center and eventually reduces the dark-conductivity. At an optimum pressure of ∼30 mTorr, the transport of ample SiH3-radicals and atomic-H from the plasma appears instrumental in producing the p-nc-Si thin film with high-crystallinity (∼77%) in columnar-like growth morphology and adequately wide optical bandgap (∼1.88 eV). Substitution of the Si-atoms, primarily residing in the lattice within the core of Si-nanocrystals, by the electrically-active four-fold-coordinated B-atoms (B4-) generates high-density of free charge-carriers and contributes to high electrical-conductivity (∼1 S cm−1) of the room-temperature grown p-nc-Si thin film on the flexible PET-substrate, which seems suitable for the fabrication of low-cost flexible-electronics, including Si solar-cells.

Structural, optical and surface properties of sol–gel-derived boron-doped ZnO films for photocatalytic applications

Structural, optical and surface properties of sol–gel-derived boron-doped ZnO films for photocatalytic applications

Interstitial Boron-Doped Nanoporous Palladium Film for Electro-Reduction of Nitrogen to Ammonia

Interstitial Boron-Doped Nanoporous Palladium Film for Electro-Reduction of Nitrogen to Ammonia

Solution-Processable Growth and Characterization of Dandelion-like ZnO:B Microflower Structures

Intrinsic and dandelion-like microflower nano-rod structures of boron-doped ZnO thin films were synthesized with an ecofriendly and cost-effective chemical bath deposition technique from an aqueous solution of zinc nitrate hexahdyrate [Zn(NO3)2.6H2O] as a precursor solution and boric acid as a doping solution. The boron concentrations were 0.1, 0.3, 0.5, 1.0, 3.0, 5.0, and 7.0 by volume. Scanning electron micrographs showed that doping with boron appears to hinder the vertical alignment of crystallites. Additionally, independent hexagonal nano-rod structures were observed to coalesce together to form dandelion-like structures on the film’s surface. The atomic ratio of the elements was determined via the X-ray photoemission spectrum technique. There were no substantial changes in the vibration structure of the film upon doping in terms of the Raman spectra. The optical band gap of ZnO (3.28 eV) decreased with B doping. The band gap of the ZnO:B film varied between 3.18 and 3.22 eV. The activation energy of the ZnO was calculated as 0.051 eV, whereas that of the ZnO:B film containing 1.0% B was calculated as 0.013 eV at low temperatures (273–348 K), versus 0.072 eV and 0.183 eV at high temperatures (348–523 K), respectively. Consequently, it can be interpreted that the 1% B-doped ZnO, which has the lowest activation energy at both low and high temperatures, may find some application areas such as in sensors for gases and in solar cells.

Achievement and electrochemical responsiveness of advanced boron-doped ultrananocrystalline diamond on highly ordered titanium dioxide nanotubes

Boron-doped ultrananocrystalline diamond grown on titanium dioxide nanotubes without seeding pre-treatment (B-UNCDWS/TDNT/Ti), as a porous composite, was successfully achieved. Innovative approaches concerning the highly ordered TDNT production as well as its singular diamond formation by hot filament chemical vapor deposition (CVD) were explored. The B-UNCD homogeneous cluster progress on the TDNT porous walls as a function of the growth times from 1 to 7 h led to remarkable composite morphologies, keeping the TDNT porosity, where the TiO2 – TiC conversion dominated the renucleation process facilitating the nanometric scale control. Scanning electron microscopy images confirmed the continuous ultrananocrystalline formation as nanoclusters on the TDNT walls with their size evolution as a function of growth time also showing an increase in the CVD diamond ballas clusters. Raman spectra and X-Ray patterns exhibited the diamond characteristics with defined peaks and TiC formation, as expected. The ID(220)/(111) and ID(311)/(111) ratio intensities pointed out the films governed by (220) diamond phase, due to their high renucleation process. Besides, the intensity ratios for both TiC (111) and TiC (200) phases with D(111) peak showed a carbon atoms competition between surface and bulk diffusion on the TiC layer. The electrode reversibility evaluated from cyclic voltammetry curves followed the quasi-reversible criteria for all samples, confirming their promising performance. Mott-Shottky plots are in good agreement with Raman spectra for boron-doped films from 1018 to 1019 B.cm−3 where the highest doped diamond was obtained for the thickest films of 5 and 7 h.

Structures, Electronic Properties and Carrier Transport Mechanisms of Si Nano-Crystalline Embedded in the Amorphous SiC Films with Various Si/C Ratios.

Recent investigations of fundamental electronic properties (especially the carrier transport mechanisms) of Si nanocrystal embedded in the amorphous SiC films are highly desired in order to further develop their applications in nano-electronic and optoelectronic devices. Here, Boron-doped Si nanocrystals embedded in the amorphous SiC films were prepared by thermal annealing of Boron-doped amorphous Si-rich SiC films with various Si/C ratios. Carrier transport properties in combination with microstructural characteristics were investigated via temperature dependence Hall effect measurements. It should be pointed out that Hall mobilities, carrier concentrations as well as conductivities in films were increased with Si/C ratio, which could be reached to the maximum of 7.2 cm2/V∙s, 4.6 × 1019 cm−3 and 87.5 S∙cm−1, respectively. Notably, different kinds of carrier transport behaviors, such as Mott variable-range hopping, multiple phonon hopping, percolation hopping and thermally activation conduction that play an important role in the transport process, were identified within different temperature ranges (10 K~400 K) in the films of different Si/C ratio. The changes from Mott variable-range hopping process to thermally activation conduction process with temperature were observed and discussed in detail.