Molecular dynamic simulation on temperature evolution of SiC under directional microwave radiation

Silicon carbide (SiC) is widely used as the substrate for high power electronic devices as well as susceptors for microwave (MW) heating. The dynamics of microwave interaction with SiC is not fully understood, especially at the material boundaries. In this paper, we used the molecular dynamics simulation method to study the temperature evolution during the microwave absorption of SiC under various amplitudes and frequencies of the microwave electric field. Directional MW heating of a SiC crystal slab bounded by surfaces along [100] crystallographic direction shows significantly faster melting when the field is applied parallel to the surface compared to when applied perpendicular

Transcriptional Subtyping and CD8 Immunohistochemistry Identifies Patients With Stage II and III Colorectal Cancer With Poor Prognosis Who Benefit From Adjuvant Chemotherapy

This work was funded by Cancer Research UK: C212/A13721 and C11884/A24387Peer reviewedPublisher PD

2014 IEEE 40th Photovoltaic Specialist Conference, PVSC 2014

In this work, we conducted Capacitance-Voltage (C-V) measurement on an inverted Metal-Oxide-Semiconductor (MOS) structure device with in-situ Boron (B) doped silicon quantum dot (QD) materials as the semiconductor layer. The highly conductive P++ Si (0.001-0.005 ohmic.cm) and thermal oxide worked as the metallic gate and the dielectric layer respectively in this MOS structure. We demonstrated that there were less parasitic components in the inverted MOS in vertical structure than MOS in lateral structure. C-V curves showed clear accumulation, depletion and inversion regions as well as a frequency dispersion effect. An analysis on the equivalent circuit model and material electrical properties was presented to explain the frequency dispersion effect. We propose that the frequency dependent shift could be eliminated by removing the frequency-dependent capacitor component (Cm) in series with the ideal MOS equivalent circuit. This capacitor is possibly due to the long dielectric relaxation time in the Si QD material due to the high density of deep defects and the high resistivity. The estimated average doping level extracted from corrected C-V curves is high despite high resistivity

Boron doped Si rich oxide/SiO<inf>2</inf> and silicon rich nitride/SiN<inf>x</inf> bilayers on molybdenum-fused silica substrates for vertically structured Si quantum dot solar cells

Vertically structured Si quantum dots (QDs) solar cells with molybdenum (Mo) interlayer on quartz substrates would overcome current crowding effects found in mesa-structured cells. This study investigates the compatibility between boron (B) doped Si QDs bilayers and Mo-fused silica substrate. Both Si/SiO2 and Si/SiNx based QDs bilayers were studied. The material compatibility under high temperature treatment was assessed by examining Si crystallinity, microstress, thin film adhesion, and Mo oxidation. It was observed that the presence of Mo interlayer enhanced the Si QDs size confinement, crystalline fraction, and QDs size uniformity. The use of B doping was preferred compared to phosphine (PH3) doping studied previously in terms of better surface and interface properties by reducing oxidized spots on the film. Though crack formation due to thermal mismatch after annealing remained, methods to overcome this problem were proposed in this paper. Schematic diagram to fabricate full vertical structured Si QDs solar cells was also suggested

Controlled Ostwald ripening mediated grain growth for smooth perovskite morphology and enhanced device performance

Here we report, a novel two-step dipping technique via post-immersion polar solvent engineering for controlled secondary grain growth (Ostwald Ripening) to fabricate efficient mixed organic cation based MA0.6FA0.4PbI3 perovskite solar cell (PSC) in conjunction with low temperature (140 °C) processed sol-gel ZnO ETL for full process compatibility with flexible substrates. The reported MTD-SE method (stands for Modified Two Step Dipping - Solvent Engineering) limits the grain coarsening effect during post-immersion stage of two-step dipping method and provides substantially smooth perovskite surface morphology for enhanced charge transport properties compared to conventional two-step techniques by means of controlled Ostwald Ripening process. The grain coarsening process and concomitant irregular grain size distribution are judiciously controlled by increasing the chemical potential or free energy change (ΔG) of the system at the post-immersion. The photovoltaic performance and photo-current hysteresis phenomena of the reported MTD-SE PSC have been compared with PSCs fabricated with conventional two-step techniques, incorporating 2-Propanol or ethyl alcohol as dipping solvents. The enhanced device performance of MTD-SE PSCs is correlated with the conducive role of the evenly distributed grain boundaries in them, which act as carrier dissociation interfaces and carrier transport pathways to charge selective contacts for superior charge separation and extraction properties. Adding to the merits, MTD-SE PSCs also demonstrate significantly suppressed photo-current hysteretic behaviour which has been elucidated in the context of faster ion migration kinetics with the increased grain boundaries, which exhibit higher ionic diffusivity. The favourable ion migration kinetics with MTD-SE PSC have also been comprehensively analysed from the frequency-dependent capacitive spectra

Passivation effects in B doped self-assembled Si nanocrystals

Doping of semiconductor nanocrystals has enabled their widespread technological application in optoelectronics and micro/nano-electronics. In this work, boron-doped self-assembled silicon nanocrystal samples have been grown and characterised using Electron Spin Resonance and photoluminescence spectroscopy. The passivation effects of boron on the interface dangling bonds have been investigated. Addition of boron dopants is found to compensate the active dangling bonds at the interface, and this is confirmed by an increase in photoluminescence intensity. Further addition of dopants is found to reduce the photoluminescence intensity by decreasing the minority carrier lifetime as a result of the increased number of non-radiative processes

Analysis of burn-in photo degradation in low bandgap polymer PTB7 using photothermal deflection spectroscopy

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