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Single GaAs nanowire based photodetector fabricated by dielectrophoresis
摘要： Mechanical manipulation of nanowires (NWs) for their integration in electronics is still problematic because of their reduced dimensions, risking to produce mechanical damage to the NW structure and electronic properties during the assembly process. In this regard, contactless NW manipulation based methods using non-uniform electric fields, like dielectrophoresis (DEP) are usually much softer than mechanical methods, offering a less destructive alternative for integrating nanostructures in electronic devices. Here, we report a feasible and reproducible dielectrophoretic method to assemble single GaAs NWs (with radius 35–50 nm, and lengths 3–5 μm) on conductive electrodes layout with assembly yields above 90% per site, and alignment yields of 95%. The electrical characteristics of the dielectrophoretic contact formed between a GaAs NW and conductive electrodes have been measured, observing Schottky barrier like contacts. Our results also show the fast fabrication of diodes with rectifying characteristics due to the formation of a low-resistance contact between the Ga catalytic droplet at the tip of the NW when using Al doped ZnO as electrode. The current-voltage characteristics of a single Ga-terminated GaAs NW measured in dark and under illumination exhibit a strong sensitivity to visible light under forward bias conditions (around two orders of magnitude), mainly produced by a change on the series resistance of the device.
关键词： chemical beam epitaxy,optoelectronics,dielectrophoresis,nanowire assembly,GaAs nanowire photodetector,nanofabrication
更新于2025-09-23 15:19:57
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High-specific-detectivity, low-dark-current Ge nanowire metal-semiconductor-metal photodetectors fabricated by Ge condensation method
摘要： We have investigated Ge nanowire (NW) metal-semiconductor-metal (MSM) photodetectors with high specific detectivity and low dark current, in which various sizes Ge NWs were fabricated by three-dimensional (3D) Ge condensation techniques. It has been demonstrated that the photocurrent gain increases significantly from 6.31×104 to 4.47×106 with the reduction of Ge NW width from 170 to 35 nm. A low dark current of 5.1 nA and an ultra-high specific detectivity of 1.26×1014 cm·Hz1/2·W-1 at 560 nm under 0.51 V bias are achieved for the 35 nm wide Ge NW photodetector. It has been proposed that the interface states provided by SiGeOx formed during Ge condensation process serve as electron traps to generate photogating effect, resulting in high photocurrent gain and high specific detectivity in the MSM photodetector. The fully complementary metal-oxide-semiconductor (CMOS) compatible and scalable process suggests a great potential of the Ge NW for low cost, high performance near infrared photodetectors.
关键词： gain,Ge nanowire photodetector,Ge condensation technique,photogating effect
更新于2025-09-12 10:27:22
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Low-cost photodetector architectures fabricated at room-temperature using nano-engineered silicon wafer and sol-gel TiO2 – based heterostructures
摘要： In the last decades, significant research has been done on the nanocrystalline forms of titanium dioxide (tio2). Amorphous TiO2 has not been studied intensively despite being significantly less expensive compared to crystalline TiO2. This study reveals significant improvement in UV-VIS photodetection properties from heterostructures fabricated in ambient environment using n-type silicon nanowire arrays and amorphous TiO2 sol-gel. Our ultra-low-cost UV-VIS photodetectors can cover a wide range of applications. We report fast rise/decay time constants of 0.23 ms/0.17 ms and high responsivity up-to 6.0 A/W in the UV and 25.0 A/W in the visible range under low (1 V) external bias. The large surface area due to the nanowire array architecture leads to 2 orders of magnitude enhancement in photo-response. Besides the final electrode deposition, the entire device fabrication is performed using low-cost, all solution-based methods in ambient conditions. These low-cost UV-Visible broadband photodetectors can potentially serve a wide range of applications.
关键词： heterostructures,UV-VIS photodetection,TiO2,silicon nanowire,photodetector
更新于2025-09-11 14:15:04