Solid solutions of InSb-ZnS heterosystem — primary converters of semiconductor sensors
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2021-01-01 |
| Journal | Omsk Scientific Bulletin |
| Authors | I. A. Kirovskaya, N. V. Chernous, Е. В. Миронова, А. О. Ekkert |
| Institutions | ORCID, Omsk State Technical University |
| Citations | 2 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled “Executive Summary”The research focuses on synthesizing and characterizing InSb-ZnS solid solutions for use as primary transducers in semiconductor gas sensors.
- Material Synthesis: Solid solutions (InSb)x(ZnS)1-x were successfully synthesized using isothermal diffusion, confirming the formation of substitution solid solutions with a cubic sphalerite structure.
- Structural Correlation: Bulk properties (lattice parameter ‘a’, density, particle size) show non-linear dependence on composition, with distinct extrema (minimums) observed near 77 mol.% ZnS content.
- Surface Acidity: Surfaces exposed to air are characterized as weakly acidic, with isoelectric point pH (pHiso) values ranging from 5.7 to 6.6.
- Active Centers: Surface activity is predominantly governed by Lewis acid centers (pHiso < 7), indicating high sensitivity towards basic gases.
- Sensor Application: The synthesized materials, particularly those with the lowest pHiso values, are highly recommended for manufacturing sensors designed to detect trace concentrations of basic gases, specifically ammonia (NH3).
- Research Efficiency: Established correlations between bulk properties (band gap, electronegativity difference) and surface properties (pHiso) provide a less labor-intensive pathway for identifying new, effective sensor materials.
Technical Specifications
Section titled “Technical Specifications”| Parameter | Value | Unit | Context |
|---|---|---|---|
| Synthesis Method | Isothermal Diffusion | N/A | Used controlled temperature heating program [1]. |
| Crystal Structure | Cubic Sphalerite | N/A | Confirmed structure for the solid solutions. |
| Specific Surface Area (Ssp) | 0.31 - 1.35 | m2/g | Range for the fine-dispersed powders used. |
| Lattice Parameter (a) Range | 5.41 - 6.47 | Angstrom | Varies across the InSb-ZnS composition range. |
| pHiso Range (Weakly Acidic) | 5.7 - 6.6 | Dimensionless | Surface acidity measured for air-exposed components. |
| Critical Composition (Extremum) | 77 | mol.% ZnS | Composition showing minimum in lattice parameter and particle size (ncp). |
| Band Gap (Eg) Range | 0.18 - 3.67 | eV | Correlates with increasing ZnS content (InSb to ZnS). |
| High Vacuum Pressure | 2.3·10-4 | Pa | Pressure used during thermal surface purification. |
| High Vacuum Temperature | 573 - 673 | K | Temperature range for surface purification. |
| Surface Center Type | Lewis Acid Centers | N/A | Confirmed by pHiso < 7, leading to high activity toward basic gases. |
Key Methodologies
Section titled “Key Methodologies”- Material Synthesis: Solid solutions (InSb)x(ZnS)1-x were prepared in the form of fine-dispersed powders using a proprietary method based on isothermal diffusion of the binary components (InSb, ZnS) under a controlled temperature heating program [1].
- Structural Characterization (XRD): X-ray diffraction was performed using a BRUKERAXS D8 Advance Diffractometer (CuK-radiation, λ=0.154056 nm). Analysis confirmed the cubic sphalerite structure, verified solid solution formation via line shifts, and determined lattice parameters (a) and interplanar distances (dhkl).
- Microscopy and Elemental Analysis: Scanning Electron Microscopy (SEM, JSM-5700) equipped with Energy-Dispersive X-ray analysis (EDX, JED-2300) was used to verify elemental composition and analyze surface morphology and particle size distribution.
- Surface Chemical Analysis (IR Spectroscopy): Fourier-transform infrared spectroscopy (Infra-LUM FT-02 with MNPO attachment, 400-4000 cm-1 range) was used to identify adsorbed species (H2O, OH groups, carbon compounds) and surface oxidation products on air-exposed samples.
- Surface Purification: Samples were subjected to high-vacuum thermal treatment (P ≈ 2.3·10-4 Pa, T = 573-673 K) to remove adsorbed impurities and oxide phases prior to detailed surface studies.
- Acid-Base Property Determination: The hydrolytic adsorption method was employed to determine the isoelectric point pH (pHiso). This value characterized the surface acidity (weakly acidic, pHiso < 7) and confirmed the relative dominance of Lewis acid centers.
Commercial Applications
Section titled “Commercial Applications”The InSb-ZnS solid solutions, optimized for surface acidity and high activity toward basic gases, are primarily targeted for advanced sensor technology.
- Ammonia (NH3) Detection: Serving as highly sensitive primary transducers for detecting trace levels of ammonia, crucial for environmental and industrial monitoring.
- Environmental Air Quality Monitoring: Integration into portable and fixed sensors for monitoring atmospheric pollution, particularly in areas affected by agricultural runoff or industrial nitrogenous emissions.
- Industrial Safety and Process Control: Used in gas detection systems within chemical plants, refrigeration facilities, and storage areas where basic gases (like NH3) pose toxicity or corrosion risks.
- Semiconductor Research and Development: The established correlations between bulk (Eg, ΔX) and surface (pHiso) properties offer a predictive tool for developing new AIIIBV-AIIBVI based materials for various electronic and sensing applications.
- High-Performance Gas Sensors: Application in the next generation of semiconductor sensors requiring high selectivity and stability due to the controlled crystalline structure and surface chemistry.
View Original Abstract
Using the specifically developed method, solid solutions of the AIIIBV (InSb), AIIBVI (ZnS) type semiconductor compounds of various composition (InSb)x (ZnS)1-x have been obtained. According to the results of the performed X-ray, micro-, electron-microscopic studies, the obtained solid solutions are certified as substitutional solid solutions with a cubic sphalerite structure, data on multicomponent diamond-like semiconductors has been enlarged. The chemical composition of the solid solutions surfaces and binary components of the InSb-ZnS system exposed in air and in high-vacuum, high-temperature conditions have been determined. According to the results of the acid-base properties studies, the surfaces of the InSb-ZnS system components exposed in the air are assigned to the weakly acidic region (pHiso<7). The views on the predominant relative contribution of Lewis acid sites and the increased activity of surfaces toward the main gases have been stated and proved. The interrelated consistent patterns of changes in the composition of bulk and surface properties have been established. The practicability of their use for a less labour consuming search for the advanced materials intended for the sensor technology has been shown. The obtained solid solutions, specifically those with the lowest pHiso, are recommended for the manufacture of the sensors for the main gases, particularly NH3, trace contamination.