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This research aimed to investigate the feasibility of using direct amorphization of silicon induced by femtosecond laser irradiation for maskless lithography. A thin layer of amorphous silicon of predetermined pattern was first generated by irradiation by a femtosecond laser of Mega Hertz pulse frequency. The following KOH etching revealed that the amorphous silicon layer acted as an etch stop. Line width less than 1/67 the focused spot size was demonstrated and hence the proposed maskless lithography process has the potential of producing submicron and nanoscale features by employing a laser beam of shorter wavelength and a high NA focusing lens. Scanning Electron Microscope (SEM), a Micro-Raman and Energy Dispersive X-ray (EDX) spectroscopy analyses were used to evaluate the quality of amorphous layer and the etching process.

This research aimed to study the effects of laser parameters on direct silicon amorphorization. It was found that higher repetition rate of laser pulses gives smooth morphology with better repeatability. Increasing pulse duration and number of pulses were seen to increase the line width. However, increasing the number of pulses does not result in ablation of the target area. An analytical model is developed for the calculation of the average surface temperature after n-pulses; it was found that for a constant power and a constant repetition rate, an increase in the pulse number does not correspond to a significant increase in the surface temperature. Moreover, at the controlled laser power level, the surface temperature will not exceed the melting point of silicon. Therefore, thermal induced damage is not observed during the amorphization.

Gallium oxide, as an emerging semiconductor, has attracted a lot of attention among researchers due to its high band gap (4.8 eV) and a high critical field with the value of 8 MV/cm. This paper presents a review on different chemical and physical techniques for synthesis of nanostructured β-gallium oxide, as well as its properties and applications. The polymorphs of Ga2O3 are highlighted and discussed along with their transformation state to β-Ga2O3. Different processes of synthesis of thin films, nanostructures and bulk gallium oxide are reviewed. The electrical and optical properties of β-gallium oxide are also highlighted, based on the synthesis methods, and the techniques for tuning its optical and electrical properties compared. Based on this information, the current, and the possible future, applications for β-Ga2O3 nanostructures are discussed.

Spinal cord injury (SCI) is a traumatic lesion that diminishes sensory and/or motor neuronal functionality, directly affecting the quality of the patient's life. Due to the central nervous system’s (CNS)...