Suspended core-shell Pt-PtOx nanostructure for ultrasensitive hydrogen gas sensor

Abstract

High sensitivity gas sensors are typically realized using metal catalysts and nanostructured materials, utilizing non-conventional synthesis and processing techniques, incompatible with on-chip integration of sensor arrays. In this work, we report a new device architecture, suspended core-shell Pt-PtOx nanostructure that is fully CMOS-compatible. The device consists of a metal gate core, embedded within a partially suspended semiconductor shell with source and drain contacts in the anchored region. The reduced work function in suspended region, coupled with builtin electric field of metal-semiconductor junction, enables the modulation of drain current, due to room temperature Redox reactions on exposure to gas. The device architecture is validated using Pt-PtO 2 suspended nanostructure for sensing H 2 down to 200 ppb under room temperature. By exploiting catalytic activity of PtO 2 , in conjunction with its p-type semiconducting behavior, we demonstrate about two orders of magnitude improvement in sensitivity and limit of detection, compared to the sensors reported in recent literature. Pt thin film, deposited on SiO 2 , is lithographically patterned and converted into suspended Pt-PtO 2 sensor, in a single step isotropic SiO 2 etching. An optimum design space for the sensor is elucidated with the initial Pt film thickness ranging between 10 nm and 30 nm, for low power (<5 lW), room temperature operation. V C 2015 AIP Publishing LLC. [http://dx.

A highly sensitive and moisture-resistant gas sensor for diabetes diagnosis with Pt@In2O3 nanowires and a molecular sieve for protection

“…As proved by the XPS results, the peaks of Pt 4+ in the samples including Pt can be observed, indicating that a small amount of PtO 2 is formed. As already known, PtO 2 is a typical p-type material 39 ; this means that p-n junctions formed between In 2 O 3 and PtO 2 . With the formation of the p-n junctions, the carrier densities of the S1-S5 NWs also increase remarkably.…”

Controllable Anomalous n- and p-Type Photothermoelectric Effects of Platinum Oxide and Tungsten Trioxide Layers with and without Chromic Reaction

“…In fact, the binding energies of the Pt 4f XPS peaks derived from Pt 2+ and Pt 4+ , are quite similar to those derived from the PtSi species, Pt 2 Si and PtSi, respectively. , Although we assigned them to Pt 2+ and Pt 4+ and analyzed these peaks, it is more reasonable to conclude the generation of PtSi species than that of PtO x . Thus, the generation of PtO x is attributable to the p-type conduction behavior of PTO on SiO 2 because it has already been reported that PtO x (PtO and PtO 2 ) has the p-type properties. , Although no PtO x was detected by XRD, the existence of PtO x was suggested by XPS, and the prepared PTO was a mixture of Pt and PtO x , in which PtO x dominated the p-type conducting behavior. In contrast, PTO on Si was n-type, which was caused by the presence of Pt and/or PtSi species and by the absence of PtO x .…”

“…Thus, the generation of PtO x is attributable to the p-type conduction behavior of PTO SiO 2 because it has already been reported that PtO x (PtO and PtO 2 ) has the ptype properties. 42,43 Although no PtO x was detected by XRD, the existence of PtO x was suggested by XPS, and the prepared PTO was a mixture of Pt and PtO x , in which PtO x dominated the p-type conducting behavior. In contrast, PTO on Si was ntype, which was caused by the presence of Pt and/or PtSi species and by the absence of PtO x .…”

Photoinduced in Situ Deposition of Uniform and Well-Dispersed PtO2 Nanoparticles on ZnO Nanorods for Efficient Catalytic Reduction of 4-Nitrophenol

“…In particular, the C 1s peak comes from the sample holder. In the high-resolution XPS (Figure 4b), the Pt 4f 7/2 and Pt 4f 5/2 peaks at 75.0 and 78.3 eV, respectively, are ascribed to the chemical state of Pt 4+ , 10,34 further proving the formation of PtO 2 on the surface of PtO 2 / ZnO-30. After H 2 treatment, the PtO 2 nanoparticles can be reduced to metallic state Pt particles.…”