RU2231052C1 - Method of manufacture of thin-film sensor for determination of concentration of methane in gas mixture - Google Patents

Abstract

FIELD: semiconductor sensory engineering.

SUBSTANCE: proposed method includes applying gas sensitive layer of chemically pure magnesium phthalocyanine no more than 15 nm in thickness on substrate made from devitrified glass and provided with raster electrodes made from anti-corrosive alloy; this layer is subjected to technological activation and alloying by air oxygen.

EFFECT: facilitated procedure; low cost.

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Description

The invention relates to semiconductor sensor technology and can be used for the manufacture of inexpensive and easy to manufacture sensors for determining the concentration of methane in a gas environment.

A known method of manufacturing a thin-film sensor for gas analysis (patent PL 137250, class G 01 N 27/00, 1989), which includes applying a gas-sensitive layer to a substrate with electrodes and technological activation of this layer.

The disadvantages of the sensor obtained by this method include low sensitivity (18 mg / m ³ ), long regeneration time (15 min), high operating temperature (150 ° C) and the complexity of the manufacturing technology (multiple - 11 cycles of gas-sensitive layer heating).

A known method of manufacturing a thin-film sensor for the analysis of ammonia in a gas environment (patent RU 2172951, class G 01 N 27/12, 2001), adopted for the prototype, which consists in the following.

A thin layer (20 nm) of copper phthalocyanine purified by chemical methods is applied to a ceramic substrate with raster electrodes in vacuum by thermal sublimation. The temperature of the substrate during the condensation of copper phthalocyanine from the gas phase was maintained at 195–205 ° С. After spraying, the copper phthalocyanine layer was doped with oxygen in a low vacuum.

However, in the thin-film sensor obtained by this method for gas analysis during operation, the following disadvantages were identified:

1. The large area of the sensor is 6.25 cm ² (25 × 25 mm).

2. High operating temperature - 95 ° C.

3. High operating voltage - up to 36 V.

4. The need for sensor regeneration (warming up to 135 ° C for 4-5 minutes).

The invention is aimed at simplifying the manufacturing technology of a gas sensor and reducing its cost.

This is achieved by the fact that a gas-sensitive layer of a chemically refined organic semiconductor with a thickness of not more than 15 nm is deposited on a ceramic substrate with raster electrodes of an anticorrosive alloy, which is subjected to technochemical activation and doping with atmospheric oxygen. As an organic semiconductor used MgPc.

Figure 1 shows a semiconductor methane gas sensor, where 1 is a raster electrodes; 2 - a layer of magnesium phthalocyanine; 3 - sitallovy substrate. Figure 2 shows the dependence of the sensitivity (R _g / R ₀ ) of the sensor on the concentration of methane. Figure 3 shows the dependence of the decimal logarithm of the sensitivity of the sensor on the concentration of methane.

The proposed method of manufacturing a thin-film sensor for the analysis of methane in a gas environment is as follows:

1. A thin layer (15 nm) is applied by thermal sublimation on a ceramic substrate (Fig. 1, pos. 3) with scanning electrodes made of an anticorrosive alloy (Fig. 1, pos. 1), heated to 200 ° C in a vacuum of 10 ^-3 Pa. ) magnesium phthalocyanine (figure 1, position 2), purified by chemical methods.

2. Doping of the MgPc layer with atmospheric oxygen.

New in the proposed method compared to the prototype is:

1. the use of an optimum thickness of not more than 15 nm as the gas-sensitive layer of the organic semiconductor MgPc;

2. the area of the glass substrate is reduced to 1 cm ² due to the use of an organic semiconductor of magnesium phthalocyanine (MgPc) having a conductivity of σ = 10 ^-7 Ohm ^-1 · m ^-1 , which is two orders of magnitude higher than that of copper phthalocyanine (σ = 2 · 10 ^-10 Ohm ^-1 · m ^-1 );

3. doping with atmospheric oxygen.

The manufacture of a thin-film sensor for analyzing methane in a gaseous medium by the proposed method made it possible to obtain a sensitivity for measuring methane concentration (C) of 0.05% in air volume and a linear dependence of IgR _g / R _о on concentration (Fig. 2), to reduce the consumption of an organic semiconductor for manufacturing, Simplify sensor manufacturing technology and improve specifications.

Tests of thin-film sensors for measuring methane concentration in a gas medium were carried out at t = 50 ° C and a voltage of 5 V. The dependence of the sensor readings on the ammonia concentration was measured in the range of 0.05-0.5% in the air volume. The dependence of the resistance of the sensor on the concentration of methane gas is shown in Fig.3. To return the resistance does not require additional heating and time. The sensors have high stability parameters. The error in measuring the initial resistance was not more than 1%.

The table presents a comparison of the characteristics of the claimed method and prototype.

Claims (1)

A method of manufacturing a thin-film sensor for determining the concentration of methane in a gaseous medium, including applying a gas-sensitive layer of a chemically purified organic semiconductor to a ceramic metal substrate with raster electrodes of an anticorrosive alloy, technological activation of this layer and heating of the gas-sensitive layer, characterized in that on a ceramic metal substrate with an area of 1 cm ² a layer of organic magnesium phthalocyanine semiconductor is applied, with a thickness of not more than 15 nm, which is then doped with acid Air Odom.

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