This study introduces a new hybrid field emitter architecture by integrating vertically aligned silicon nanowires (SiNWs), synthesized by RT metal-assisted chemical etching (MACE), with nanocrystalline diamond-like carbon (nc-DLC) films produced by RF-PECVD from (CH4 + H-2) precursor gases. Unlike typical DLC-coated SiNW emitters, the optimized nc-DLC coating, rich in sp(3) C-C nanocrystalline domains (sp(3) C-C similar to 72%), significantly improves the field emission performance of SiNWs through a synergistic interplay of better nanocrystallinity, a lower electron tunnelling barrier, the negative-electron-affinity (NEA) characteristic of the nc-DLC surface, and geometric field enhancement. A systematic investigation on the nc-DLC coating duration (T-DLC) reveals a critical trade-off between the nanostructure ordering and tip morphology, identifying an optimum deposition time (T-DLC = 40 min) where emission performance is maximized, with a low turn-on field (E-ON) of 4.6 V/mu m and a high field enhancement factor (beta) of 1676, outperforming uncoated SiNWs (E-ON = 5.8 V/mu m, beta = 1108). For the T-DLC = 40 min sample, an optimal balance between sp(3) and sp(2) bonding is achieved, where the increased sp(3) content lowers the electron affinity and tunnelling barrier. In contrast, the remaining sp(2) pathways preserve efficient carrier transport. Additionally, post-deposition thermal activation at 150 degrees C significantly improves electron emission, reducing E-ON to 3.2 V/mu m and increasing beta to 3321, providing a cost-effective and scalable method to optimize electron emission without high-temperature annealing. This combined approach of controlled nc-DLC growth and gentle thermal tuning sets a new standard for high-performance, thermally responsive vacuum microelectronic SiNW/nc-DLC hybrid emitters.

Developing highly conductive p-type nanocrystalline silicon (p-nc-Si) at low substrate temperatures remains a significant challenge due to insufficient crystallinity and high defect densities. In this work, B-doped nc-Si thin films were prepared in low-pressure inductively-coupled SiH4 plasma, without additional H-2-dilution, where efficient in-situ generation of high-density atomic-H enables the desired film growth at a substrate temperature (T-S) as low as similar to 30 degrees C. At this temperature, the film maintains substantial crystallinity (similar to 80%), moderate conductivity (similar to 1 S cm(-1)), and a wide optical band gap (similar to 1.82 eV). At higher TS, increased thermal energy enhances crystallinity and promotes a faster growth rate through thermodynamically favored <220> orientation, resulting in a significant I-<220>/I-<111> ratio (similar to 9.05) and conductivity of similar to 10 S cm(-1). A more crystalline network with low H-content causes a notable shift of the Fermi level within the band-tail states, leading to two separate Meyer-Neldel characteristic energies. The novelty of the work lies in demonstrating a low-temperature route to obtaining the preferred <220>-oriented, highly conductive p-nc-Si thin film without any additional H-2-dilution or post-annealing. The combination of excellent crystallinity, preferred orientation, wide optical band gap, and strong optoelectronic performance makes these films promising as a doped contact layer in silicon solar cells.

By accumulating the unique properties of ZnO, MoS2, and rGO, such as high surface area, excellent charge transport capabilities, and enhanced light absorption, collectively in the ZnO/MoS2/rGO (ZMR) nanocomposite heterostructures synthesized through a conventional hydrothermal process, the material architecture has been integrated as the photoanodes in dye-sensitized solar cells (DSSCs). The synergistic effects arising from the combination of different component materials in the heterostructure nanocomposite photoanode led to improved optimum photo-current density (J(SC)) similar to 14.97 mA cm(-2), open-circuit voltage (V-OC) similar to 0.75 V, and fill factor (FF) similar to 65.2%, eventually improving the DSSC's photo-conversion efficiency (eta) to similar to 7.32%, which remains more than 2 times higher than that of a pure ZnO-photoanode configured device. The optimal performance of the DSSC is achieved in the ZMR-0.35 photoanode configuration, in which MoS2 provides effective surface coverage to suppress ZnO dissolution and reduce charge recombination; besides, rGO ensures efficient electron transport and interfacial charge extraction. The abundance of these heterostructure nanocomposite materials and their facile fabrication techniques make their integration alluring for large-scale, cost-effective, and environmentally benign solar energy conversion applications.

The reacting gas pre-heating is presented as a means to enhance the diamond nucleation density in the diamond-like carbon (DLC) films with embedded nanocrystallinity (NCD). Utilizing C2H2 as the precursor gas having low ionization potential, allows for faster NCD-embedded DLC growth. The additions of H-2, a conventional dilution gas, along with CO2, a weak oxidant, increase the chemical activity of the growth precursors and aids in the removal of a-C phase from the growth site. Notably, the bandgap widens from 3.40 to 3.48 eV, while the sp(3)/sp(2) ratio increases from 1.9 to 2.38. Raman spectroscopy reveals higher I-Dia/I-G (0.85), I-Dia/I-D (0.94), alongside a lower I-D/I-G ratio (0.90) for the film grown at the optimum gas-pre-heating temperature (T-G = 250 degrees C) demonstrate the superiority of the less-stressed DLC network, with higher optical transmittance of similar to 93% at 600 nm. The DLC matrix developed at a substrate-temperature (T-S) similar to 300 degrees C holds a good quality nano-diamond phase (grain size similar to 8-10 nm), containing distinct trans-PA peaks (1171 and 1497 cm(-1)) and diamond peaks (1333 cm(-1)) as the signature. The preheating of the source gas mixture elevates the precursor gas molecules' vibrational energy states, facilitating the conversion of C2H2 to CH3, which is energetically favorable for diamond nucleation.

Diamond-like carbon (DLC) films with good crystalline properties, extended optical band gap, and suitably low refractive index were grown on glass substrates, from (CH4 + H-2)-plasma, using a radio frequency capacitively-coupled plasma-enhanced CVD system. Firstly, the impact of modifying the deposition pressure on the properties of the DLC films was monitored. Subsequently, the effect of varying the H-2/CH4 flow rate ratio was studied at the optimized plasma pressure conditions. The other deposition parameters included a substrate temperature of 450 degrees C with a low RF power of 250 W. The optimized pressure of 4 Torr and flow ratio H-2/CH4 = 1 resulted in a crystalline DLC film with a minimum I-D/I-G ratio (0.63), a maximum I-Dia/I-G (0.69), and significant I-Dia/I-D (1.09), along with a high sp(3) C-C content of similar to 67 %. The crystalline characteristics of the DLC film were identified by the intense <111> X-ray diffraction (XRD) peak at 2 theta = similar to 43.8 degrees (grain size similar to 14.6 nm), and the corresponding lattice planes by the high-resolution TEM images. Besides, a wide E-g similar to 3.65 eV from a high transmittance of similar to 85% for wavelengths beyond 400 nm, along with the lowest magnitudes of R-550 similar to 5.20%, n(550) similar to 1.57, and k(550) similar to 0.084, demonstrated the DLC film ideal as ARC layer in single junction p-i-n Si solar cells. Using the DLC ARC layer in 'Glass/DLC/FZO/p-nc-SiOx:H/i-nc-Si:H/n-a-Si:H/Al' configuration thin film solar cell yields an efficiency, eta similar to 6.84% which is > 25% higher than its counterpart without the DLC ARC layer.

The synthesis of three-dimensional carbon nanostructures without templates remains a substantial challenge. The present research enables skillfully generating horizontally -aligned carbon-nanorod-arrays (HA-CNRA), using microwave plasma -enhanced chemical vapor deposition (MW-PECVD) on quartz substrates coated with Co catalyst layers annealed at diverse temperatures. In this method, a gas mixture comprising C 2 H 2 , H 2 , and CO 2 was used for the CNRA growth at a low substrate temperature of -300 degrees C. Electron -microscopy observation confirms the autonomous growth of individual hollow CNRs. A discernible peak at 1340 cm -1 , G band peak at 1596 cm -1 , and 2670 cm -1 peak (2D band) were observed, indicating a well -graphitized feature of the CNRs, which was further ascertained by the corresponding X-ray diffraction planes of (002) and (101) orientations. In the optimally grown film, a homogeneous array of nanorods with an average diameter of -450 nm was obtained. The C 1 s spectra peaked at 284.6 eV confirming the presence of crystalline sp 2 -hybridized nanorods. The novelty of the work lies in enabling the Co catalyst -assisted template -free growth of HA-CNRA by low -temperature MW-CVD, utilizing the reactant atomic species like H and O from the (C 2 H 2 + H 2 + CO 2 )-plasma and preserving the growth continuity through a specific shadow masking configuration deployed atop the developing plane, thereby inducting a diffuse plasma on the substrate and restricting the direct collision of energetic particles with the developing network. Due to the adjustable size, shape, and advantageous architectural characteristics, horizontally -aligned CNRA manifests significant potential as electrode materials for energy storage applications, specifically in batteries and electrochemical capacitors.

The diamond-like carbon (DLC) thin films having intrinsic nanocrystalline diamond (NCD) components were synthesized on bare glass substrates at 300 degrees C, employing a (C2H2/CO2/H-2/) gas mixture in MW-PECVD. Relevant influence of the weak oxidant fraction [F = CO2/(CO2 + C2H2)] in the plasma on the specific hybridized constituents (sp(3) and sp(2)) in the C-network, optical transmission characteristics of the film, and its accomplished degree of nanocrystallinity were investigated. A substantial segment of the NCD was achieved in the DLC matrix. An optimized diamond-phase component corresponding to the minimized bond angle disorder in the matrix was accounted from the manifestation of the maxima of I-Dia/I-G and I-Dia/I-D simultaneous to the minimum of I-D/I-G ratio in Raman response, along with an allied diamond peak appearing near 1332 cm(-1). The optimal DLC film at F = 0.23 revealed a wide optical band gap (E-g) of similar to 3.60 eV, similar to 59% sp(3)-hybridized C component of the diamond phase, and a significant sp(3)/sp(2) ratio of similar to 2.1. The film microstructure seemed homogeneous with uniformly distributed NCDs of average diameter similar to 7.5 nm and dominant < 111 > crystallographic orientation. The sp(3)/sp(2) fraction in the film matrix has been correlated directly to the I-Dia/I-G and I-Dia/I-D, and inversely to I-D/I-G ratios of the Raman data. Atomic-O, including atomic-H, remains instrumental in chemical reactions, facilitating the etching of graphitic and a-C phases while preserving the superior sp(3)-hybridized NCD component growing uninterruptedly in the DLC network that subsists shielded from the high-energy ion impact within secondary plasma under the shadow mask.

Vertically oriented arrays of Si nanowires (SiNWs) with high aspect ratios are grown uniformly over large areas by a simple yet inexpensive one-step room-temperature Ag-assisted chemical etching of bulk c-Si, following an uninterrupted reduction-oxidation-termination mechanism at the Ag/Si interface. Using the chemically grown SiNWs as the n-c-Si core and radio-frequency plasma-assisted chemical vapor deposition-grown p-a-Si:H as the shell layer, the p/n-heterojunction SiNW array solar cells, in core-shell configuration, are produced with an optimum photovoltaic (PV) conversion efficiency, eta similar to 4.71%. Considering that the PV performance remains limited by factors like lattice mismatch, parasitic absorption of photons, faster photogenerated charge carrier recombination, etc., the cell configurations were upgraded in various combinations. Introducing a thin i-a-Si:H passivation shell layer improved the cell performance in its p/i/n configuration. Substituting the i-a-Si:H by the wider band gap and higher conductivity i-nc-Si:H layer further boosted the PV characteristics, via improved passivation and minimizing junction inequality at the i/n-interface. Analogous reduction of lattice mismatch and carrier recombination at p/i-junction increased the PV aptitude, using the p-nc-Si:H layer. Improving the window layer functionality in sequence, by using a wide optical gap p-nc-SiOx:H shell layer, further facilitated an increased V-OC similar to 0.59 V, improved FF similar to 51% under an extended spectral response, and yielded the maximum eta similar to 9.21%, involving the p-nc-SiOx:H/i-nc-Si:H/n-c-SiNW advanced core-shell configuration of the heterojunction solar cells (HJSCs). The unique optical characteristics, comprising superior antireflection attributes and omnidirectional light absorption over a broad wavelength range at diverse angles of incidence, demonstrate sequential improvements in the external quantum efficiency response of the SiNW-based HJSC devices. The reduced photon reflection loss stems from optical impedance matching involving the refractive index gradient from the air to the bulk-Si substrate via that of the SiNWs, comprising a significant light scattering effect manifested by their subwavelength structures.

A Ge top layer of thickness ∼1.2μm was grown on the top Si of a silicon-on-insulator (SOI) wafer by plasma-enhanced chemical vapor deposition (PECVD) technique followed by rapid thermal annealing (RTA) makes this a GeSOI wafer. The top active Ge layer on RTA recrystallizes into a compact layer of Ge nanocrystals with lattice constants close to those of the Ge single crystal enabling device fabrication and a partially suspended Ge microline photodetector was fabricated that can show adequate photo gain. It was established through simulation that the partial suspension of the microline is necessary to isolate the microlines from the bulk of the wafer which inhibits carrier recombination by the underlying oxide layer.

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 degrees 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 Bdoped DLC film possessed enhanced electrical conductivity (sigma RT) of -3.02 x10- 5 S cm-1 relative to the intrinsic DLC films, a corresponding minimum of activation energy (Delta EH) (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.

The nc-Ge thin films are grown at a moderately low temperature (similar to 220 degrees C) in rf PECVD via optimizing the GeH4 plasma with H-2-dilution, within 97.5 <= D(H-2)(%) <= 99.5. At elevated D(H-2), while the bonded H-content in the matrix reduces, the film's crystallinity and dc conductivity increase. However, the optical band gap widens for 97.5 <= D(H-2)(%) <= 98.5, via the elevated quantum confinement effect from the increased number of Ge-ncs of dimension below Bohr radius. Conversely, for D(H-2) >= 98.5%, switching in the quantum effect in larger-sized Ge-ncs induces the band gap narrowing. Significantly reduced ultra-nanocrystalline-Ge (unc-Ge) component occupying the grain boundary zone, minimizes the contribution of grain-boundary defects. However, the persistent amorphous Ge matrix becomes highly defective and less dense, and those induce enhanced O-absorption from the ambient in the dominant Ge-O-x (x < 2) configuration. On increased crystallinity, the activation energies of dipole relaxation (Delta E-tau) and resistance (Delta E) in the impedance data reduce dominantly in the a-Ge component than its nc-Ge counterpart, which occurs identically for the dc conductivity when the amorphous component in the matrix sharply disappears at increased D(H-2) > 98.5%. A narrow band gap (similar to 0.90 eV), conducting (sigma(d) similar to 3.0 x10(-2) S cm(-1)), and photosensitive nc-Ge network, involving dominant <111>-oriented Ge-ncs (similar to 35.2 nm) of enriched volume fraction (X-C similar to 90.2%), obtained at D(H-2) similar to 99.5%, seems extremely useful for need-based applications as a narrow band gap absorber layer in the bottom sub-cell of flexible high-efficiency cost-effective multijunction thin film solar cells.

ZnO-nanostructures, having low in-vivo toxicity and bio-degradability, need appropriate architectures, aiding maximal photon absorption and minimal charge recombination, for endorsing efficient photocatalysis. Accordingly, ZnO-nanorods are impregnated with Ag2O-nanoparticles and embedded on g-C3N4-nanosheets (ZAO/GCN), the photocatalytic performance of which is primarily attributable to augmented optical absorption via narrow band gap, fast propagation of photo-electrons with reduced recombination, inducted by the synergistic interactions between ZnO/Ag2O/g-C3N4, and the improved specific surface area and pore-volume of g-C3N4 sheets providing efficient adsorption of the dye-molecules. Subsequently, metallic Ag0 formation helps scavenge the valence electrons of Ag2O nanoparticles, thus encouraging e–/h+ detachment and faster dye-degradation. Eventually, photo dye-degradation starts by forming g-C3N4/ZnO/Ag2O double-junction and accelerates by g-C3N4/ZnO/Ag0/Ag2O triple-junction via inducting the unique bi-phasic two-slope photocatalysis phenomena. During photocatalysis, h+ acts as the predominant reactive species, O2•–, e–, and OH• being substantially less relevant. On increasing g-C3N4 loading, dye-degradation improves with corresponding faster crossover time (tC) via the enhanced contribution of trapped conduction band electrons (etr−) of g-C3N4 generating surplus Ag0. The optimized ZAO/GCN1.0 photocatalyst demonstrates the visible-light MB dye-degradation efficiency of ∼94.5% with a rate-constant (∼0.0933 min−1) ∼10 times superior to ZnO, which, including the robust design and recyclability, could pave the way for advanced water disinfection.

TiO2 has the proven capability of catalytically decomposing pollutants under light illumination, thereby embracing potential applications in wastewater management. The photocatalytic dye degradation activity is largely controlled by the optical band gap that dictates the extent of electron-hole pair generation via photon absorption, and the recombination kinetics of charges. In this context, the material's work function governs how easily the charge carriers can be transferred at the dye-adsorbed photocatalytically active sites. Accordingly, nanocrystalline TiO2 thin films are grown in the anatase phase with < 101 > orientation, using RF magnetron sputtering at 200 degrees C. Besides studying the film's structural morphology, optical band gap, and elemental composition, the electronic properties are extensively investigated. The work function of the material was controlled by varying the O-vacancy-dependent Ti3+ bonding configuration in the network. It has been demonstrated how the photocatalytic methylene blue dye degradation activity of the nanocrystalline TiO2 films of predominantly the anatase phase improves on reducing the sputtering pressure during deposition. At a low deposition pressure of 20 mTorr, a low work function of similar to 4.2 eV of the film, resulting from the formation of a Ti3+-bond through the O vacancies in the network, potentially increases its carrier lifetime and delivers the superior photocatalytic activity (similar to 82.7% dye degradation with a rate constant of k similar to 0.0073 min(-1)) via silently facilitating fast electron transfer from the photocatalyst to the dye in the aqueous solution. The higher stoichiometric film prepared at p = 40 mTorr exhibits an inferior photocatalytic activity (similar to 20.4% dye degradation with a rate constant of k similar to 0.0009 min(-1)), as retarded by its higher work function of similar to 4.62 eV, despite retaining a relatively low band gap. Thus, without using any heterojunction or extrinsically doped photocatalyst, the dye degradation can be controlled simply by reducing the work function of nanocrystalline TiO2 thin films via controlling the O-vacancy-dependent Ti3+ bonding in its self-doped network.

Post-deposition O absorption is a common issue in low-temperature grown nc-Ge films, that makes the material unstable and induces high n-type electrical conductivity similar to 10(-2) S cm(-1). An attempt has been made to mitigate the oxygen absorption issue through B doping of the nc-Ge thin film network at a low deposition temperature of similar to 220 degrees C, employing a conventional capacitively coupled PECVD. At a B2H6 flow rate of 3.0 sccm, the incorporation of a restricted quantity of B maintains a narrow band gap of similar to 1.04 eV, significantly low conductivity of similar to 6.76 x10(-7) S cm(-1), activation energy similar to 398 meV, and photosensitivity of 6.0. Spectroscopic studies indicated that B doping facilitated reduced O-intake in the nc-Ge matrix, possibly via passivating the grain boundary defects and dangling bonds in the amorphous matrix and inducing the preferential absorption of O atoms in the Ge-O-2 configuration compared to its Ge-O-x (x < 2) counterpart. The diminished O-induced carriers and the supplied acceptor levels by the B dopants compensate for the inherent n-type carrier concentration. However, at higher B2H6 flow rates, significant B incorporation in the film matrix introduces numerous defects, degrading the crystallinity, despite increasing its p-type conductivity to 2.16 x10(-5) S cm(-1) and maintaining a narrow band gap. Organized switching in the type of conductivity from the n-type to p-type ensues via gradually rising the B-dopants within the nc-Ge thin film network during its growth, which deserves attention for specific device applications.

The effects of increasing substrate negative dc bias on growing the boron-doped diamond-like carbon (B-DLC) films are extensively studied, following a single -step and low-pressure plasma processing. With the optimum bias of -80 V, the B-DLC films exhibit good crystalline properties corresponding to accomplishing the (I D /I G ) min -0.75, (I Dia /I D ) max -1.49, and (I Dia /I G ) max -1.11 values in the Raman data. The X-ray photoelectronic spectroscopy results demonstrate attaining -57.29% of the sp 3 -hybridized C - C bonds and a significant B 4 - C component of -24.25%. A high electrical conductivity (c5 D -1.15 x10 -4 S cm - 1 ) was attained with coherent low activation energy in the above-room-temperature regime ( Delta E H -111 meV). Microscopic studies reveal a smooth structural surface, distinct (111) crystalline planes, and a broad optical gap of -3.70 eV. Interestingly, the Meyer-Neldel characteristic energy (E MN ), as estimated from the ln(c5 0 ) vs. Delta E H plot, demonstrates a positive-tonegative sign-reversal while increasing the bias across -80 V, signifying a transition from the non-degenerate to a degenerate semiconductor-like characteristic at elevated negative substrate bias. Thus, in the above-roomtemperature regime, the B-DLC material pursues a switching in its electronic band characteristics when prepared across a threshold in the substrate bias of -80 V under the present plasma conditions. While in the belowroom-temperature regime, Mott's variable-range-hopping phenomena prevails arbitrarily at any substrate bias.

This study reports a direct approach to synthesizing vertically aligned carbon nanorod arrays (VA-CNRA) using microwave plasma-enhanced chemical vapor deposition (MW-PECVD) at 300 °C, on Cobalt (Co) catalyst nanoparticles grown by thermal annealing (750 °C) of 10 nm thick Co layer deposited by Radio frequency (RF) magnetron sputtering. To grow the VA-CNRA, the gas ratio in the plasma was optimized, focusing on the kinetics of the source gas dissociation and recombination. The reduced concentrations of acetylene (C2H2) impede the optimal alignment of CNRA in the absence of the steric hindrance, resulting in their horizontal growth along the direction of gas flow via the “kite-mechanism”. However, at a higher gas flow ratio, the attractive van der Waals potential among the CNRs was anticipated to induce aggregation when they arrive in proximity and vertical growth alignment of the nanorods via the higher deposition rates. Carbon nanorod films were analyzed using various spectroscopic techniques to understand the growth orientations, which suggests that the carbon nanorods were formed via the base-growth mechanism. Nano flower-like VA-CNRA were formed at higher C2H2/H2 ratios. Notably, a distinct flower-like structure with whisker-like nanostructure petals was formed at a C2H2/H2 flow ratio of ∼0.57. Compared to other nanorod structures, VA-CNRA, grown at optimal gas ratio, exhibited superior crystalline graphite, with 76% sp2 C=C bonding along with a maximum of I2D/IG, and a minimum of ID/IG intensity ratio in the Raman data. High-resolution TEM confirmed robust growth of CNRs, with an average diameter of ∼370 ±3 nm. This innovative method enables large-scale production of VA-CNRA with high surface areas for energy applications.

One convenient approach to minimize the surface recombination loss in Si is to passivate the surface dangling bonds by depositing a thin TiO2 layer on the bulk Si. Besides, the p-Si/TiO2 interface can initiate hole-blocking and facilitate efficient electron transport through the TiO2 layer; thereby, promoting the extraction of electrons for efficient onward utilization. In this context, the current investigation involves studying how the Ti3+ donor states, produced by deliberately introducing O-vacancies controlled by changing the plasma pressure in the RF-magnetron sputtering chamber during the growth of the TiO2 thin films, can change the material's Fermi level and work function and modify the band bending and band offset as well as the fixed oxide charge density in the p-Si/TiO2 heterojunction interface. The TiO2/p-Si interface has been studied through capacitance-voltage (C-V) analysis to determine the interface parameters such as fixed oxide charge, the density of interface traps, and the dielectric constant of TiO2. The studied hole-blocking property of the interface has been correlated to the photoresponsivity of the metal-oxide-semiconductor (MOS) structure. The MOS device fabricated at a pressure of 30 mTorr displays a large saturation current (15.95 μA cm–2) when subjected to a positive gate bias, facilitated by the relatively low conduction band offset (ΔEC ~0.20eV), significant positive fixed oxide charge (+1.18 ×1011cm–2) and the interface trap density (1.03 ×1012cm–2), which enhanced the transport of minority carrier electrons from the p-Si to the metal, resulting in a good photo responsivity ~0.158 AW–1 and photo gain of ~37.5 under white light illumination. Optimum hole-blocking and surface passivate characteristics of the TiO2/p-Si interface together may facilitate fabricating improved heterojunction Si solar cells.

Phosphorous doping in the nc-Si network induces gradually reduced crystallinity; however, preferential growth along < 220 >-oriented crystallites promotes the columnar-like growth morphology. At optimum doping, substitution by donor P+-atoms in the c-Si lattice contributes surplus free electrons and high carrier mobility, resulting in superior electrical conductivity in the n-nc-Si network. An elevated doping leads to incorporating elemental P0 atoms in the interstitial position or forming P-Si-H clusters and generating voids between the crystalline columns. Segregation of defects contributes to decreasing carrier mobility and reducing conductivity after diminishing crystallinity and narrowing the optical band gap. By precisely controlling the growth at 250 degrees C and efficient electrically active doping by P+-atoms, n-nc-Si thin films with superior dark conductivity ( 101 S cm-1) are produced in which the percolation of charge carriers through the crystalline columns could facilitate stacked-layer devices. The optimum n-nc-Si thin films are used as the emitter layers in n-nc-Si/p-c-Si heterojunction solar cells (HJSCs). Furthermore, an ultrathin a-Si:H buffer layer on the p-c-Si minimizes the junction carrier recombination loss, and subsequent postdeposition short-time H-plasma treatment (PSHPT) ensures seeds for superior nanocrystallization in the n-nc-Si emitter layer. The n-nc-Si/(PSHPT)i-nc-Si(buffer layer)/p-c-Si HJSC delivers a PV conversion efficiency, eta 12.35%, via a reasonable fill factor of 0.647 and sensible JSC of 32.75 mA cm-2. Further improvement in the PV performance could be possible using suitably thinner p-c-Si wafers, harmonizing with the effective carrier diffusion length, and fabricating a high-quality passivation structure on the backside.