Abstract
The electric properties and chemical and thermal stability of gallium oxide β-Ga2O3 make it a promising material for a wide variety of electronic devices, including chemiresistive gas sensors. However, p-type doping of β-Ga2O3 still remains a challenge. A β-Ga2O3 epitaxial layer with a highly developed surface was synthesized on gold electrodes on a Al2O3 substrate via a Halide Vapor Phase Epitaxy (HVPE) method. The epitaxial layer was impregnated with an aqueous colloidal solution of gold nanoparticles with an average diameter of Au nanoparticle less than 5 nm. Electrical impedance of the layer was measured before and after modification with the Au nanoparticles in an ambient atmosphere, in dry nitrogen, and in air containing dimethyl sulfide C2H6S (DMS). After the impregnation of the β-Ga2O3 epitaxial layer with Au nanoparticles, its conductance increased, and its electric response to air containing DMS had been inversed. The introduction of Au nanoparticles at the surface of the metal oxide was responsible for the formation of an internal depleted region and p-type conductivity at the surface.
Highlights
Academic Editors: Eduard LlobetThe properties of gallium oxide β-Ga2 O3, such as ultrawide bandgap, high breakdown voltage, high carrier mobility, and chemical and thermal stability; and the fact that high quality bulk crystals can be fabricated with melt-growth methods [1,2] predestine β-Ga2 O3 to be the material of choice for high power and high frequency electronic devices [3], solar-blind photodetectors [4,5], UV emitters, transparent conductive films, and gas sensors [6,7]
The analysis of the results has shown that the conductivity of this metal oxide increases slightly with the concentration of dimethyl sulfide (DMS) (Figure 11)
A β-Ga2 O3 epitaxial layer surface-modified with Au nanoparticles was investigated
Summary
The properties of gallium oxide β-Ga2 O3 , such as ultrawide bandgap, high breakdown voltage, high carrier mobility, and chemical and thermal stability; and the fact that high quality bulk crystals (and monocrystalline substrates) can be fabricated with melt-growth methods [1,2] predestine β-Ga2 O3 to be the material of choice for high power and high frequency electronic devices [3], solar-blind photodetectors [4,5], UV emitters, transparent conductive films, and gas sensors [6,7]. In the vast majority of these methods, the synthesis is carried out at reduced pressure, or in a vacuum; regardless of the conditions of synthesis, their common goal is to produce smooth, homogenous layers for later applications in semiconductor devices. For gas sensor applications, layers with highly developed surfaces are desirable. It is widely believed that materials with large active surface areas are characterized by very good sensitivity [13,14]
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