Vol.:(0123456789) 1 3 Journal of Theoretical and Applied Physics https://doi.org/10.1007/s40094-020-00368-3 RESEARCH Fabrication and characterization of PSi/nanometal hybrid structures by laser for CO gas sensor Amer Badr Dheyab 1  · Safaa Idan Mohammed 1  · Marwa Kamal Mustafa 1  · Rasha Saad Fayadh 1  · Noor Luay Hussein 1 Received: 4 September 2019 / Accepted: 28 January 2020 © Islamic Azad University 2020 Abstract Mesoporous silicon (mesoPSi) layers fabricated by the photoelectrochemical etching (PECE) method in hydrofluoric acid (HF) are active as carbon monoxide gas sensors. The modified porous silicon (PSi) can be used with noble metals to manu- facture an effective gas sensor. Embedded gold, platinum, and palladium nanoparticles Au, Pt, and Pd-NPs could modify the surface morphology of mesoPSi and form mesoPSi/AuPtPd-NPs hybrid structures through a simple and dipping process in fixed salt concentrations. The morphology of the hybrid structures has been studied using scanning electron microscopy and X-ray diffraction. The prepared gas sensor has measured the electrical characteristics at room temperature. Shape, nanopar- ticle size, and specific surface area strongly influenced the current–voltage characteristics. The results show that Au, Pd, and Pt-NPs sizes prepared by the dipping process for mesopore-like structures were in the range from 0.64 to 7.53 nm. Besides, considerable improvements in the response, recovery times and sensitivity of gas sensor were noticed when decreasing the incorporated Au, Pd, and Pt-NPs to the mesoPSi matrix. Keywords MesoPSi · SEM · Gas sensing · Photoelectrochemical · AuPtPd-NPs hybrid structures Introduction Porous silicon (PSi) is a new material of importance due to its morphological properties. The PSi performs like a heatproof in the application of a heating plate [1]. The main advantage of PSi gas sensor is the low consumption of power and the short transient thermal times called ‘passive processes.’ This makes PSi material suitable for thermally insulated microheat due to its large surface area. The PSi layer can be approximately a quick and excellent etching method. Besides, the PSi layer acts like the gas detection device with optical, electrical or thermal measurements. PSi gas sensitive is considered simple and of low cost, and it relies on resistance. It can be of high sensitivity and called a sensor of active processes or active sensor [2]. The gas-detecting devices are considered ideal, and there are some points to be taken into account [3]: (a) The lowest value of gas in the laboratory can be sensed or identified through what is called ‘sensor.’ (b) The capability of gas sensors in identifying a precise gas between gas combinations is defined as selectivity. (c) The interval of the time when the gas concentration spreads has a precise value to this sensor by producing a warning signal that it is the response time. (d) Returning the sensor to its initial detection status later is defined as reversibility. (e) Stability. Modification of the PSi layer was found by combining the constituent nanomaterial and the metal oxide layer as an effective means of improving the gas sensor performance [4]. In these studies, the PSi aspects of the substrate were covered with a thin layer of gold. The resulting room tem- perature devices were extra sensitive to the voltage used in the CO 2 gas; the nanostructured PSi had a greater response than other similar sensors. The performance of nanosilicon wires was studied; it was modified using nanoparticles of gold and platinum, as CO 2 gas sensors. A strong dependence was found on the type of metallic nanoparticle [5]. Whether loading using Pt, Pd, and thin SnO 2 films could improve their ability to detect unused sensors was investigated [6]. * Safaa Idan Mohammed safaadali431@gmail.com 1 Ministry of Science and Technology, Baghdad, Iraq