Fabrication of Gas-Sensor Chips Based on Silicon–Carbon Films Obtained by Electrochemical Deposition

Abstract

In this study, we designed two types of gas-sensor chips with silicon–carbon film, doped with CuO, as the sensitive layer. The first type of gas-sensor chip consists of an Al2O3 substrate with a conductive chromium sublayer of ~10 nm thickness and 200 Ω/□ surface resistance, deposited by magnetron sputtering. The second type was fabricated via the electrochemical deposition of a silicon–carbon film onto a dielectric substrate with copper electrodes formed by photoelectrochemical etching. The gas sensors are sensitive to the presence of CO and CH4 impurities in the air at operating temperatures above 150 °C, and demonstrated p- (type-1) and n-type (type-2) conductivity. The type-1 gas sensor showed fast response and recovery time but low sensitivity, while the type-2 sensor was characterized by high sensitivity but longer response and recovery time. The silicon–carbon films were characterized by the presence of the hexagonal 6H SiC polytype with the impurities of the rhombohedral 15 R SiC phase. XRD analysis revealed the presence of a CuO phase.

Investigation of Adsorption Kinetics on the Surface of a Copper-Containing Silicon–Carbon Gas Sensor: Gas Identification

“…A gas-sensitive layer was formed on interdigitated electrodes using the electrochemical deposition technique [47][48][49]. In the first stage, the deposition of the pure silicon-carbon film from methanol and hexamethyldisilazane (HMDSN) (ratio 9:1) solution was carried out for 40 min at 150 V. In the second stage, copper acetate (0.14 wt.%) was added to the electrolyte, and the film deposition continued for 5 min at 50 V. Finally, a methanol/HMDSN (ratio 9:1) solution was deposited onto the silicon-carbon film layer for 40 min at 150 V. Then, the films were annealed at 200 • C for 2 h. Interdigitated electrodes were formed via the vacuum vapor deposition of Cr/Cu/Cr (h Cr = 15 nm, h Cu = 2 µm) layers on the Al 2 O 3 substrate with the following laser demetallization (MicroSET-M Granite RA, Russia): step between electrodes-50 µm; electrode width-50 µm.…”

Electrochemical Deposition of Silicon-Carbon Films: A Study on the Nucleation and Growth Mechanism

“…There are some reports that have demonstrated the possibility of the electrochemical deposition of DLC films from the organic liquids such as methanol [12], acetonitrile [13], dimethylsulfoxide [14], and lithium acetylide in dimethylsulfoxide [15], in ambient conditions. However, earlier, we reported the electrochemical deposition of silicon-carbon films from methanol/ethanol and hexamethyldisilazane (HMDS) solution [16,17]. However, in the development of the synthesis of a new material, the deposition kinetics is one of the first components to be studied in detail to ensure reproducibility.…”