Longitudinal Grain Boundaries Research Articles

Bundle-Type Columnar Cu2O Photoabsorbers with Vertical Grain Boundaries Fabricated Using Instant Strike-Processed Metallic Seeds and Their Enhanced Photoelectrochemical Efficiency

The design to control grain boundaries (GBs) causing recombination losses as planar defects in the absorbing layers is an essential strategy for the development of highly efficient photoelectrochemical (PEC) reaction systems. We propose a method to design a progressive bundle-type columnar structure as an alternative to single crystals with the least defects, where the GBs are parallel to the charge transport movement and the electric field direction. An instant strike bias (0.01 s and −1 V vs Ag/AgCl) in the same electrolytes induces the formation of island-shaped metallic Cu nanoparticles in the initial stage. These act as seed crystals for controlling Cu₂O growth evolution, resulting in dramatically high-density Cu₂O nuclei. This is followed by the deposition of bundle-type columnar Cu₂O with longitudinal GBs, contrary to the typical randomly crystallized Cu₂O. Metallic Cu seeds with a stronger electric field than that of the exposed indium tin oxide (ITO) region provide selective crystallization sites for Cu₂O growth along the ⟨111⟩ ionic bonding. Despite the instant strike interval, the p-type Cu₂O photoelectrodes retained an outstanding photocurrent density of 5.2 mA cm–² at 0 VRHE and an onset potential of 0.7 VRHE because of the highly improved charge transport and transfer efficiencies inside Cu₂O induced by effectively suppressing charge scattering in the GBs. The impedance measurements depict the overall decrease in the total resistance, charge-transfer resistance, and the photoabsorber/electrode interface resistance of the PEC systems with the introduction of the instant strike process.

Effect of Latitudinal and Longitudinal Grain Boundaries on the Characteristics of Polycrystalline Silicon MOSFET Devices

The MOSFETs, Complementary MOS-ICs are the core switch devices of current which also critically affects the ICs. For higher IC performance the present era has shifted to the device scaling to sub-50nm range TFT (thin film transistor) based MOSFET which involves complex fabrication process. The presence of grain boundaries greatly affects the characteristics of these devices. Present paper describes dependence of output characteristics inpolycrystalline silicon MOSFET devices on the longitudinal and latitudinal grain boundaries (GBs) have been investigated theoretically. It is observed that in both latitudinal and longitudinal GBs, the GB scattering potential ‘qφ’ and the GB distribution parameter ‘s’ are equally involved. At all values of gate voltages the contribution in drain current of the device is more due to latitudinal GBs in comparison to longitudinal GBs. However, at high gate voltages longitudinal GBs play a significant role in the drain current of the device.The theoretical computations of the model are synonymous to the experimental work.

Anisotropic conduction behavior in metal-induced laterally crystallized polycrystalline silicon thin films

The conduction behavior of metal-induced laterally crystallized (MILC) polycrystalline silicon (poly-Si) was studied and compared to that of the conventional solid-phase crystallized and low-pressure chemical vapor deposited poly-Si. MILC poly-Si was found to exhibit superior electrical properties, with significantly lower grain-boundary (GB) trap density, as well as much higher carrier mobility and conductivity. Furthermore, a unique anisotropic conduction behavior was discovered in MILC poly-Si, with the resistivity and its activation energy showing remarkable difference for conduction transverse or parallel to the MILC direction. These phenomena have been related to the fluctuation of the potential barrier associated with the longitudinal GBs separating the relatively ordered elongated grains in MILC poly-Si.