RU2584205C2 - MATERIAL FOR CONVERSION OF VACUUM ULTRAVIOLET RADIATION INTO VISIBLE RANGE RADIATION IN FORM OF AMORPHOUS FILM OF SILICON OXIDE SiO2Sx ON SILICON SUBSTRATE - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to luminescent materials for conversion of vacuum ultraviolet radiation into visible range radiation, intended for manufacture of functional elements new-generation photon devices, as well as to control of hard ultraviolet radiation in vacuum processes. Proposed material is characterised by that thickness of amorphous film of silicon oxide SiO₂S_x is 20-70 nm, and oxygen ions are contained in an amount at which stoichiometric factor x ranges from 0.01 to 0.45.

EFFECT: invention provides high intensity of blue radiation of material and absence of red luminescence while maintaining conversion of vacuum ultraviolet radiation into visible radiation.

1 cl, 3 dwg, 1 tbl, 5 ex

Description

The invention relates to luminescent materials for the conversion of vacuum ultraviolet radiation into visible radiation in the form of an amorphous silicon oxide film SiO ₂ S _X on a silicon substrate, designed to create functional elements of a new generation of photonic devices, for use in photosensorics, solar energy, aerospace instrumentation in particular for the power supply of navigation and control systems for unmanned aerial vehicles, as well as for controlling hard ultraviolet of radiation in vacuum processes, e.g., in the manufacture of microcircuits of 32nm or more "thin" technologies.

Known [ZhTF, 2012, v. 82, no. 2, pp. 153-155] the properties of luminescent materials based on (CaO · 0.5Al ₂ O ₃ · 5SiO ₂ ): Eu and (CaO · 0.2Al ₂ O ₃ · SiO ₂ ): Eu with the addition of B ₂ O ₃ in an amount of 3 wt.%, allowing their use as materials for the conversion of near-ultraviolet radiation (peak emission 3.2 eV or 380 nm) into visible radiation (350 ÷ 675 nm, 1.84 ÷ 3.54 eV).

The above known materials provide conversion to visible light only of near ultraviolet radiation, there is no possibility of conversion of vacuum ultraviolet radiation.

Closest to the proposed one is the luminescent material described in the article [Journal of Non-Crystalline Solids 357 (2011) 1977-1980] in the form of an amorphous silicon oxide film (S ⁺ ) amorphous SiO ₂ : S _X film with a thickness of 500 nm on a silicon substrate, operating as a material for the conversion of hard (vacuum) ultraviolet radiation (9.0 ÷ 10.5 eV or 137.6 ÷ 118 nm) into visible radiation (1.7 ÷ 1.94 and 2.5 ÷ 3.2 eV or 728 , 8 ÷ 638.7 and 495.6 ÷ 387.2 nm).

The disadvantage of the prototype material is the presence in the visible radiation spectrum of several components (1.7 ÷ 1.94 and 2.5 ÷ 3.2 eV), namely the red, blue, blue and partially purple component with a predominance of the blue component. In this case, the glow has a mixed, non-monochrome spectrum.

The objective of the invention is to provide a material for the conversion of vacuum ultraviolet radiation into visible radiation, having an increased intensity of blue glow and greater monochrome radiation.

To solve this problem, the material for the conversion of vacuum ultraviolet radiation into visible radiation in the form of an amorphous silicon oxide film SiO ₂ S _X on a silicon substrate is characterized in that the thickness of the amorphous silicon oxide film SiO ₂ is 20 ÷ 70 nm, and sulfur ions are contained in an amount at which the stoichiometric coefficient "x" is in the range from 0.01 to 0.45.

The technical result of the use of the proposed material is to increase the conversion efficiency of vacuum ultraviolet radiation into a visible glow, namely, an increase in the intensity of blue radiation by 1.3 ÷ 1.5 times and ensuring greater monochrome radiation. The latter is achieved due to the fact that there is no red stripe in the radiation of the proposed material.

When the thickness of the amorphous film of silicon oxide is less than 20 nm, the structure of the material degrades and its luminescent properties deteriorate due to an increase in the number of structural defects that are centers of luminescence quenching. With a film thickness of more than 70 nm, the technology of obtaining the material is complicated, the use of an ion source of increased power and an increase in implantation time are required, which is impractical.

When the stoichiometric coefficient "x" is less than 0.01, the luminescence intensity decreases due to the low concentration of the luminescence centers.

When the stoichiometric coefficient “x” is greater than 0.45, red glow centers appear in the proposed material, which worsens the monochromaticity of the radiation, in addition, the luminescent properties deteriorate - the effect of concentration quenching of luminescence arises.

The figure 1 shows the radiation spectra of known and proposed materials, the figure 2 shows the spectrum of the exciting vacuum radiation, while the vertical axes show the radiation intensity in relative units (rel. Units), the horizontal axis shows the photon energy (eV), in the figure 3 - calibration interdependence of energy E and film thickness d.

FIG. one:

A is the emission spectrum of a known luminescent material in the form of an amorphous silicon oxide implanted with sulfur ions SiO ₂ : S _x 500 nm thick film on a silicon substrate [Journal of Non-Crystalline Solids 357 (2011) 1977-1980, Figure 1 (S-related centers) ];

B - emission spectrum of the proposed luminescent material in the form of an amorphous silicon oxide film SiO ₂ S _x , where x = 0.27, the film thickness is 48 nm.

FIG. 2 - excitation spectrum of photoluminescence of the proposed luminescent material in the field of vacuum ultraviolet radiation.

FIG. 3 shows the dependence of the energy E of implantable S ⁺ ions (vertical axis, keV) used on the preparation of the proposed material on the required thickness d of an amorphous silicon oxide SiO ₂ film (horizontal axis, nm).

The proposed material for converting vacuum ultraviolet radiation into visible radiation in the form of an amorphous silicon oxide SiO ₂ film on a silicon substrate is obtained by introducing sulfur ions into the specified film by implantation, followed by annealing at a temperature of 700 ÷ 900 ° C for 0.5 ÷ 1 hour in a dry atmosphere nitrogen, implantation is carried out with ion energy, the value of which is determined by the formula

where E is the ion energy, keV;

d is the thickness of the amorphous film of silicon dioxide, is selected in the range from 20 to 70 nm;

and with fluence defined by the formula

where F is the fluence, ion / cm ² ;

x is a stoichiometric coefficient, a dimensionless quantity, is selected in the range from 0.01 to 0.45;

d is the thickness of the amorphous film of silicon dioxide, is selected in the range from 20 to 70 nm.

The implantation of sulfur ions into an amorphous film of silicon oxide SiO ₂ on a silicon substrate is carried out using an ion source operating in continuous mode with the parameters calculated in accordance with formulas (1) and (2) and vacuum (1.4 ÷ 2.5) · 10 ^-4 Torr Before irradiation, samples of the material are washed in alcohol in an ultrasonic bath. Annealing is carried out in an atmosphere of dry nitrogen using an electric resistance furnace (type NT 40/16).

The obtained material samples are plane-parallel plates with an area of 1 cm ² , a thickness of 0.5 mm, with a surface of optical quality. The surface layer of each sample consists of an amorphous film of silicon oxide implanted with sulfur ions SiO ₂ S _x , including S _x ions and point defects created during the implantation of sulfur ions. The underlying sample base consists of undoped silica. The photoluminescence of the obtained material was excited by vacuum ultraviolet radiation (Fig. 3) with photon energies in the range of 8.5–10.5 eV using a DESY synchrotron (Germany) through a monochromator. Luminescent spectra were recorded by a Hamamatsu R6358P photomultiplier.

The table shows the parameters of sample 1 of the known prototype material and several samples 2, 3, 4 and 5 of the proposed material. The luminescent emission spectrum of sample 1 of the prototype material is shown in FIG. 1, A. The emission spectra of samples 2, 4, and 5 correspond in shape to the radiation spectrum of sample 3 (Fig. 1, B), differing in the radiation intensities indicated in the table.

The following are examples of samples of the proposed material. The numbers of the examples correspond to the numbers of the samples in the table.

Example 1 (prototype). The material was obtained by implanting S ⁺ ions into a sample in the form of an amorphous silicon oxide film 500 nm thick on a silicon substrate at an ion energy of 150 keV and a fluence of 5 × 10 ¹⁶ ion / cm ² . Annealing was carried out in an atmosphere of dry nitrogen at a temperature of 900 ° C for 1 hour. In the obtained sample, the intensity of the peak of red radiation with an energy of 1.83 eV is 0.2 Rel. units The visible radiation of such material is mixed, contains red, blue, blue and partially violet components with a predominance of the blue component with an energy of 2.82 eV, which has a relative intensity of 1.0 Rel. units

Example 2. The material was obtained by implanting S ⁺ ions into a sample in the form of an amorphous silicon oxide film with a thickness of 20 nm on a silicon substrate with the ion energies calculated by formulas (1) and (2) of 13.3 keV and a fluence of 4.4 · 10 ¹⁵ ion / cm ² . Annealing was carried out in an atmosphere of dry nitrogen at a temperature of 850 ° C for 50 minutes. The intensity of the peak of red radiation with an energy of 1.83 eV is equal to zero. The radiation of the obtained material is mixed, but without a red band, while the intensity of blue radiation with an energy of 2.82 eV is increased and equal to 1.3 Rel. units

Example 3. The material was obtained by implantation of S ⁺ ions in a sample in the form of an amorphous silicon oxide film 30 nm thick on a silicon substrate with the ion energies of 21.3 keV and fluence 6 · 10 ¹⁵ ion / cm ² calculated by formulas (1) and (2) . Annealing was carried out in an atmosphere of dry nitrogen at a temperature of 800 ° C for 45 minutes. The intensity of the peak of red radiation with an energy of 1.83 eV is equal to zero. The radiation of the obtained material is mixed, but without a red band, while the intensity of blue radiation with an energy of 2.82 eV is increased and equal to 1.5 Rel. units

Example 4. The material was obtained by implantation of S ⁺ ions in a sample in the form of an amorphous silicon oxide film with a thickness of 45 nm on a silicon substrate with the ion energies calculated by formulas (1) and (2) of 33.3 keV and a fluence of 2.4 · 10 ¹⁶ ion / cm ² . Annealing was carried out in an atmosphere of dry nitrogen at a temperature of 800 ° C for 40 minutes. The intensity of the peak of red radiation with an energy of 1.83 eV is equal to zero. The radiation of the obtained material is mixed, but without red radiation, while the intensity of blue radiation with an energy of 2.82 eV is increased and equal to 1.5 Rel. units

Example 5. The material was obtained by implantation of S ⁺ ions in a sample in the form of an amorphous silicon oxide film 70 nm thick on a silicon substrate with ion energies of 53.3 keV and fluence 7 · 10 ¹⁶ ion / cm ² calculated by formulas (1) and (2) . Annealing was carried out in an atmosphere of dry nitrogen at a temperature of 750 ° C for 30 minutes. The intensity of the peak of red radiation with an energy of 1.83 eV is equal to zero. The radiation of the obtained material is mixed, but without a red band, while the intensity of blue radiation with an energy of 2.82 eV is increased and equal to 1.4 Rel. units

Claims (1)

Material for converting vacuum ultraviolet radiation into visible radiation in the form of an amorphous silicon oxide SiO ₂ film with sulfur ions S _x implanted in it, where x is the stoichiometric coefficient on a silicon substrate, characterized in that the thickness of the amorphous silicon oxide SiO ₂ film is 20 -70 nm, and sulfur ions are contained in an amount at which the stoichiometric coefficient "x" is in the range from 0.01 to 0.45.

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