High-efficiency reflective terahertz cross-polarization converter with broadband and wide-angle response.

In this paper, a broadband terahertz metasurface dedicated to cross-polarization conversion was designed, fabricated, and assessed. The metasurface, comprising two nested double-split rings, features an inherent insensitivity to the angle of incidence. Simulations reveal that the converter achieves a >99% polarization conversion efficiency across the 90-140 GHz range. Moreover, it maintains a >90% polarization conversion ratio (PCR), even at a 50° incidence angle. The sample, featuring 50×70 arrays, was fabricated, and the relevant experimental results align closely with the simulated outcomes. The metasurface characteristics can markedly enhance the performance of cross-polarization converters operating in the terahertz range.

A study on inorganic phase-change resist Ge2Sb2(1-x)Bi2xTe5 and its mechanism.

The inorganic phase-change photoresist Ge2Sb1.5Bi0.5Te5 has a lot of advantages such as the two-sides of the photoresist, a large difference in the etching rate between it and Si, and so on, making it a promising candidate for use in the full-vacuum manufacture of the next generation ultra-large scale integrated circuits (ULSI). However, the physical origin of its excellent properties is still unclear, hindering its improvement and the optimization of its performance. In this work, we extended the Ge2Sb1.5Bi0.5Te5 to Ge2Sb2(1-x)Bi2xTe5 (GSBT, x = 0.1, 0.25, 0.35) and further investigated their properties. Using X-ray diffraction and X-ray absorption fine structure (XAFS) analyses, we built the structures of crystalline and amorphous GSBT, and attributed the excellent physical and chemical properties of crystalline GBST to the different atomic structures compared to amorphous GBST. Moreover, we clarified that the performance of GSBT was enhanced by the increase of Bi, accompanied by a decrease of the phase-change temperature, and gave a criterion for improving GSBT.

The study on SiO2 pattern fabrication using Ge1.5Sn0.5Sb2Te5 as resists.

Ge1.5Sn0.5Sb2Te5 (GSST) can be easily induced to phase transition from amorphous state to crystalline state by a laser direct writing (LDW) system. The results show that the crystalline phase of GSST is more durable against acid solution corrosion than the amorphous phase. So nano-scale patterns and structures can be formed on the GSST film resists using laser-induced phase change and wet etching. Moreover, reactive ion etching (RIE) technology was applied to transfer these patterns onto the SiO2 substrate. The result shows to the extent that GSST material has thermal resist characteristics with high resolution and well etching selectivity to SiO2 when etched in the CHF3, which is compatibility with the future nanofabricate processing.

A Review on the Progress of Optoelectronic Devices Based on TiO2 Thin Films and Nanomaterials.

Titanium dioxide (TiO2) is a kind of wide-bandgap semiconductor. Nano-TiO2 devices exhibit size-dependent and novel photoelectric performance due to their quantum limiting effect, high absorption coefficient, high surface-volume ratio, adjustable band gap, etc. Due to their excellent electronic performance, abundant presence, and high cost performance, they are widely used in various application fields such as memory, sensors, and photodiodes. This article provides an overview of the most recent developments in the application of nanostructured TiO2-based optoelectronic devices. Various complex devices are considered, such as sensors, photodetectors, light-emitting diodes (LEDs), storage applications, and field-effect transistors (FETs). This review of recent discoveries in TiO2-based optoelectronic devices, along with summary reviews and predictions, has important implications for the development of transitional metal oxides in optoelectronic applications for researchers.

Continuous-wave Y-band planar BWO with wide tunable bandwidth.

A high performance continuous-wave (CW) backward wave oscillator (BWO) with planar slow wave structure (SWS) and sheet electron beam in Y-band is presented in this paper. The mode selection is discussed by studying the dispersion curve of SWSs, distributions of the electric field, and particle-in-cell simulation results, showing that the designed BWO operates in the fundamental mode TM11. The planar SWSs are fabricated by using the UV-LIGA technology with the processing error less than 0.003 mm. The electron gun can provide the 2.5 mm × 0.14 mm sheet electron beam with maximum current density of 57 A/cm2 at the CW mode. Experimental results show that the developed BWO can operate in the fundamental mode TM11 and generate the state-of-art output power of 182 mW at the frequency of 0.3426 THz with a large frequency tuning range from 0.318 THz to 0.359 THz.