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Yun, Jeonghoon,Jin, Chun Yan,Ahn, Jae-Hyuk,Jeon, Seokwoo,Park, Inkyu RSC Pub 2013 Nanoscale Vol.5 No.15
<P>We demonstrated novel methods for selective surface modification of silicon nanowire (SiNW) devices with catalytic metal nanoparticles by nanoscale Joule heating and local chemical reaction. The Joule heating of a SiNW generated a localized heat along the SiNW and produced endothermic reactions such as hydrothermal synthesis of nanoparticles or thermal decomposition of polymer thin films. In the first method, palladium (Pd) nanoparticles could be selectively synthesized and directly coated on a SiNW by the reduction of the Pd precursor via Joule heating of the SiNW. In the second method, a sequential process composed of thermal decomposition of a polymer, evaporation of a Pd thin film, and a lift-off process was utilized. The selective decoration of Pd nanoparticles on SiNW was successfully accomplished by using both methods. Finally, we demonstrated the applications of SiNWs decorated with Pd nanoparticles as hydrogen detectors. We also investigated the effect of self-heating of the SiNW sensor on its sensing performance.</P>
Yun, Jeonghoon,Ahn, Jae-Hyuk,Lee, Bong Jae,Moon, Dong-Il,Choi, Yang-Kyu,Park, Inkyu IOP 2016 Nanotechnology Vol.27 No.50
<P>We developed a novel method to measure local temperature at micro/nano-scale regions using selective deposition of quantum dots (QDs) as a sensitive temperature probe and measured the temperature of Joule heated silicon microwires (SiMWs) and silicon nanowires (SiNWs) by this method. The QDs are selectively coated only on the surface of the SiMWs and SiNWs by a sequential process composed of selective opening of a polymethyl methacrylate layer via Joule heating, covalent bonding of QDs, and lift-off process. The temperatures of the Joule-heated SiMWs and SiNWs can be measured by characterizing the temperature-dependent shift of photoluminescence peak of the selectively deposited QDs even with far-field optics. The validity of the extracted temperature has been also confirmed by comparing with numerical simulation results. The proposed method can potentially provide micro/nanoscale measurement of localized temperatures for a wide range of electrical and optical devices.</P>
Joule-Heated and Suspended Silicon Nanowire Based Sensor for Low-Power and Stable Hydrogen Detection
Yun, Jeonghoon,Ahn, Jae-Hyuk,Moon, Dong-Il,Choi, Yang-Kyu,Park, Inkyu American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.45
<P>We developed self-heated, suspended, and palladium-decorated silicon nanowires (Pd-SiNWs) for high-performance hydrogen (H<SUB>2</SUB>) gas sensing with low power consumption and high stability against diverse environmental noises. To prepare the Pd-SiNWs, SiNWs were fabricated by conventional complementary metal-oxide-semiconductor (CMOS) processes, and Pd nanoparticles were coated on the SiNWs by a physical vapor deposition method. Suspended Pd-SiNWs were simply obtained by etching buried oxide layer and Pd deposition. Joule heating of Pd-SiNW (<1 mW) enables the detection of H<SUB>2</SUB> gas with a faster response and without the reduction of sensitivity unlike other Pd-based H<SUB>2</SUB> gas sensors. We proposed a H<SUB>2</SUB> sensing model using oxygen adsorption on the Pd nanoparticle-coated silicon oxide surface to understand the H<SUB>2</SUB> response of Joule-heated Pd-SiNWs. A suspended Pd-SiNW showed a similar transient sensing response with around four times lower Joule heating power (147 μW) than the substrate-bound Pd-SiNW (613 μW). The effect of interfering gas on the Pd-SiNW was investigated, and it was found that the Joule heating of Pd-SiNW helps to maintain the H<SUB>2</SUB> sensing performance in humid or carbon monoxide environments.</P> [FIG OMISSION]</BR>