Corona Discharge Assisted Growth Morphology Switching of Tin-Doped Gallium Oxide for Optical Gas Sensing Applications

Abstract

To match the properties of a semiconductor to a desired application, it is crucial to control its crystal structure. Here, we show that, by implementing a corona discharge in a chemical vapor deposition process, the growth morphology of gallium oxide can be adjusted to produce nanowires and layerlike and columnar crystal structures. The three morphologies can be explained by the transition from a classic chemical vapor process to a corona-assisted chemical vapor process with directed transport. Specifically, the excitation of the carrier gas by the corona discharge is exploited as a switch to transition from a vapor–liquid–solid nanowire growth mechanism to a layer by layer growth mechanism. The second switching parameter is the substrate bias which affects the directed precursor transport and enhances the growth rate. While the switching of the morphology has no effect on the crystal phase, the photoluminescence properties of the three morphologies are different. The grown structures are used as optical gas sensors at room temperature. Tin-doped gallium oxide is shown to be capable of detecting trace amounts (200 ppm) of alcohols such as acetone, ethanol, and isopropanol. The layerlike morphology provides the highest response.

Localized and Programmable Chemical Vapor Deposition Using an Electrically Charged and Guided Molecular Flux

“…The corona generates electrons and negatively charged ions of the carrier gas nitrogen. A detailed description of the charging process and an analysis of the generated species were published before. , The negative charges drift toward the substrate, which, itself, acts as the grounded counter electrode. As substrates, silicon chips (1 cm × 1 cm) are used, which are partially masked with a 1 μm thick silicon dioxide (SiO 2 ) layer with circular openings.…”

“…Nevertheless, the EDX analysis revealed an atomic percentage of 0.13% for nitrogen. Nitrogen ions are the main species in the corona discharge because nitrogen was used as a carrier gas. ,, For those excited ions and molecules it is more likely to become incorporated in the copper oxide. Nitrogen acts as a p - type dopant in copper oxide and can thus change the optical and electrical properties of copper oxide. − The resulting doping can be actively used to adapt the material properties to the desired application.…”

Controllability of β-Ga2O3 single crystal conductivity by V doping

“…Nine phonon mode peaks were detected, derived from the undoped and V-doped β-Ga 2 O 3 crystals, which coincided with the data in the literature. 30,41 These and A (3) g ) are related to vibrations and translations of the [Ga I O 4 ] tetrahedral chains; the secondaryfrequency phonon modes (A (4) g , A (5) g and A (6) g ) are attributed to the deformation of the [Ga I O 4 ] tetrahedron and [Ga II O 6 ] octahedron; and the third-frequency phonon modes (A (8) g , A (9) g and A (10) g ) are assigned to the stretching and bending of the [Ga I O 4 ] tetrahedron. The addition of V atoms significantly inhibited A (4) g , A (5) g and A (6) g (as shown in Fig.…”

“…The continuous development of materials, has enabled the application of semiconductors in photodetectors, 1,2 solar cells, 3,4 light-emitting diodes, 5,6 and various other fields. 7–9 Beta-gallium oxide (β-Ga 2 O 3 ) crystals, as an outstanding representative of the emerging semiconductors, have been increasingly applied in semiconductor fields such as high-power electronic devices, 10 ultraviolet detectors, 11 and gas sensors 12 largely owing to their excellent material properties.…”

“…This journal is © The Royal Society of Chemistry 2022 peaks were located in B (2) g : 144 cm −1 , A (2) g : 169 cm −1 , A (3) g : 199 cm −1 , A (4) g : 320 cm −1 , A (5) g : 345 cm −1 , A (6) g : 416 cm −1 , A (8) g : 629 cm −1 , A (9) g : 658 cm −1 , and A (10) g : 766 cm −1 , and could be divided into three groups: 51,52 the primary-frequency phonon modes (B (2) g , A (2) g…”