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New trend in material engineering are composites with biological-based fillers. On of aim in biological-bases composite is how to use waste from agriculture production i.e. unused secondary products known as residues. The aim of this research is experimental investigation of wear resistance of bio-polymer composite reinforce by cotton post-harvest line residues. These residues come from cotton production as a waste which contain cotton stems and plant roots. Most of these residues are burned as energy source, but residues can find other utilization. Composites based on polymer can solve friction and wear problems in industry for their advantages as self-lubrication, light weight, easy of properties modification, etc. This research is part of wide study dealing with material utilization of post-harvest line residues. Mass loss of wear resistance at composite PCFC 500 with short fibres decrease against the matrix up to 21% on 19.28 mg.

Different material thickness with medium and high dielectric constant can impact the performance and reliability of high electron mobility transistor device. With varying the thickness of the passivation layer, the effect of it towards the device performance is still unclear. Two different insulator layers with a medium dielectric and a high dielectric constant namely Aluminium Nitride and Hafnium Oxide are used as passivation layer in AlGaN/GaN HEMT. Both material performance was simulated via COMSOL software by varying the thickness and the drain current output were compared. The passivation layer thickness of 10nm at Vds=6 V and Vgs=5 V, HfO2 outperforms AlN with the output drain current of 39 mA compared to 35 mA respectively. It was observed that HfO2 can attain higher threshold voltage, Vth as compared to the AlN because of the influence of its material properties that shows a direct proportional relationship between Vth and dielectric constant. Using high dielectric constant material like HfO2, we observe the ON-voltage gradually decreases as the thickness of the passivation layer increased. Out of all the thickness simulated for HfO2 and AlN, 10nm produced the highest drain current output instead of layer thickness of 20nm.

In this work, ray tracing is used to investigate the effects of pyramid texture angle towards light absorption and photocurrent in 250 μm-thick crystalline silicon (c-Si) absorber. Upright pyramids with texture angles of 10-50o are investigated. Planar c-Si absorber is used as a reference. When the pyramid angle increases, the broadband reflection reduces due to enhanced light scattering which leads to improved light absorption. At angle of 50o, the weighted average reflection (WAR) reduces to 14.7% and broadband light absorption increases. The optical path length enhancement increases to 12 at wavelength of 1100 nm. The reflection and photogenerated current density (Jg) exhibit an inverse relationship with increasing zenith angle. With increasing zenith angle, the reflection from the c-Si absorber increases and this results in lower light absorption and Jg. In the passivated emitter rear cell (PERC) solar cell, the planar solar cell exhibits short-circuit current density (Jsc) of 26 mA/cm2 with conversion efficiency of 13.6%. When both the pyramids and the silicon nitride (SiNx) anti-reflective coating (ARC) are incorporated on the solar cell, the Jsc increases to 39 mA/cm2 and conversion efficiency increases to 20.5%. This is attributed to the enhanced light-trapping and light-coupling effects in the device.

4H silicon carbide (SiC) based pin photodiodes with a sensitivity in the vacuum ultraviolet spectrum (VUV) demand newly developed emitter doping profiles. This work features the first ever reported 4H-SiC pin photodiodes with an implanted p-emitter and a noticeable sensitivity at a wavelength of 200 nm. As a first step, Aluminum doping profiles produced by low energy ion implantation in 4H-SiC were characterized by secondary-ion mass spectrometry (SIMS). Photodiodes using these shallow emitters are compared to one with a deep p-emitter doping profile employing IV characteristics and the spectral response. SIMS results demonstrate the possibility of shallow Alimplantation profiles using low implantation energies with all emitter profiles featuring characteristic I-V results. For some shallow doping profiles, a meassurable signal at the upper limit of the VUV spectrum could be demonstrated, paving the way towards 4H-SiC pin photodiodes with sensitivities for wavelengths below 200 nm.

In this paper, the effect of different post oxide deposition nitridation processes in NO on n-channel lateral MOSFETs fabricated on implanted 4H-SiC were investigated. In particular, the electrical behavior of the MOSFETs was deeply investigated not only in terms of SiO2/SiC interface state density and field effect mobility, but also considering the threshold voltage stability effect. The aim of this work was to explore to which extent post oxide deposition annealing in NO is beneficial for the MOS interface behavior and when their detrimental effects start to become predominant on the device performances. Here, the separation of the trapping states at the interface – either close to the conduction and valence band edges – and the near interface oxide traps are reported for the different duration of the post oxide deposition annealing. In fact, cyclic gate bias stress was employed in order to analyze the behavior of the trapping states and to correlate them with the variation of the benefits in terms of the channel mobility (that saturates at about 80 cm2V-1s-1), and on the threshold voltage instability effect. In particular, prolonged PDAs may induce an increase of the amount of trapping states close to the valence band edge and inside the insulator of about 20% and 50 %, respectively.

Direct ink writing was used for 3D printing of tubular Al2O3 membrane support. Agar-based ink mixtures were prepared as a paste with a proper viscoelastic behavior in achieving printing. Using agar only for mixing with Al2O3 slurry in preparing the ink mixtures showed the flow behavior resulting in failure to print the Al2O3 tube due to too low viscosity of the ink mixture—100 Pa at 40°C. However, the introduction of Hydroxyethyl cellulose (HEC) as thickener and Polyethylene glycol 1500 (PEG 1500) as lubricant helped improve the behavior of the ink mixtures to be more proper paste for printing. The amounts of HEC were varied from 0 to 2wt% of solid loading. At 2wt% HEC, the ink mixture was able to be printed highest, compared to the other ink mixtures. However, the 2wt% HEC-using ink mixtures possessed the highest sintering shrinkage at 12%, while its relative density was highest at 70%. The results indicated that it was possible to print the alumina membrane tube if its fidelity was improved further.