JPS61114887A - Optical recording layer for low-output semiconductor laser - Google Patents

Abstract

PURPOSE:To obtain a high-sensitivity optical recording layer which enables satisfactory information recording to be achieved even with a small-type low- output semiconductor layer, by providing a thin film of a specified chalcogenide and an organic coloring matter capable of sensitizing the thin film. CONSTITUTION:The thin chalcogenide film, which functions as a recording medium, comprises a Group 6B metal or a combination of at least 50% of a Group 6B metal and less than 50% of a Group 5B metal and/or a metal of other Group. An organic coloring matter which can be advantageously used for sensitization is, for example, a phthalocyanine coloring matter, has a quite large absorption, is chemically stable and has favorable orientation property.

Description

DETAILED DESCRIPTION OF THE INVENTION C) Industrial Application Field The present invention relates to optical recording technology. More specifically, the present invention provides a small device that can be advantageously used in optical recording materials such as laser discs and cards that record information by a change in the state of the irradiated area caused by laser beam irradiation. The present invention relates to an optical recording layer for output semiconductor laser light.

[Conventional technology]

Conventionally, an optical recording material (typically an optical disk) having a thin film of chalcogenide such as selenium-based or tellurium-based chalcogenide on a board made of glass or polymethyl methacrylate is irradiated with a laser beam, and the reflectance or transmittance of the thin film is measured. Information is recorded by changing it. In other words, this optical recording technology uses laser light irradiation to change the state of the irradiated area between a glass state (amorphous state) and a crystalline state, and uses the optical difference between the two as a memory. .

By the way, in the case of such optical recording technology, the chalcogenide thin film used as the optical recording layer is relatively transparent and the photosensitive region is short wavelength. (below) Ar laser,
) It is necessary to use a laser beam such as a le -Ne laser, or to use an external heat source to heat simultaneously with the light irradiation. The latter heating can promote the crystallization of a film, while rapid cooling, on the other hand, can advantageously change a crystalline thin film into an amorphous state.

[Problem that the invention seeks to solve]

Optical recording materials in which recording is performed using laser light, as described in the section on the prior art, are very useful as recording materials. However, for this type of recording material, it is essential to use high-output, short-wavelength laser light or to use heating in combination with light irradiation. and long wavelength (780nm
(above) cannot be used. Even if such a semiconductor laser light were used, the recording sensitivity would not be sufficient, so it would not be possible to achieve the expected information recording. Therefore, it is currently desired to provide an optical recording layer that can use a small, low-output semiconductor laser (wavelength: 780 to 850 nm).

[Means for solving problems]

As a result of research to provide a highly sensitive optical recording layer on which information can be easily written using a semiconductor laser, the present inventors found that
A low-power semiconductor laser beam characterized by having a specific chalcogenide thin film and an organic dye capable of sensitizing the thin film, that is, making the thin film capable of irradiating low-energy laser light with a wavelength of 780 nm or longer. We have discovered an optical recording layer for use.

The chalcogenide thin film acts as a recording medium and is composed of a metal of group 6B of the periodic table alone, or 50% or more of a metal of group 6B of the periodic table and less than 50% of a metal of the same group and/or Consists of a combination of metals from different groups. Selenium can be advantageously used if the recording medium is composed solely of a metal from Group 6B of the periodic table. Furthermore, if selenium is to be combined with other metals to form a recording medium, 50% or more of selenium and
Less than 50% tellurium, sulfur, germanium, antimony, bismuth, tin, lead, silicon, gallium, aluminum,
A combination with at least one of indium or zinc can be advantageously used. Similarly, tellurium alone or in combination with at least 50% tellurium and less than 50% of at least one of selenium, sulfur, germanium, antimony, bismuth, tin, lead, silicon, gallium, aluminum, indium, or zinc. It can be advantageously used as a recording medium.

Organic dyes that can be advantageously used for the purpose of sensitization in the present invention include phthalocyanine dyes, such as vanadium phthalocyanine, lead phthalocyanine, and tin phthalocyanine. In fact, such organic dyes are suitable for the purpose of the present invention because they not only exhibit fairly large absorption (at least 830 nm), but also are chemically stable and have good orientation.

In the practice of the present invention, the recording medium and the organic dye may be intermixed in a single thin layer, or alternatively, the respective thin layers may be stacked alternately to form a multilayer structure.

In recording media and organic dyes, when the former is particularly large, the absorption is small, resulting in a decrease in sensitivity, and when the latter is large, sensitization is promoted, but on the other hand, another important point is crystalline state and amorphous state Since the relationship between the states will be disrupted, these must be combined in amounts that can avoid these inconveniences. The amount of the organic dye is preferably 50% or less in volume percentage when the recording medium consists only of selenium or mainly consists of selenium, and when the recording medium consists only of tellurium or mainly consists of tellurium. When used as a component, the volume percentage is preferably 80% or less.

The optical recording layer according to the invention can be applied to a substrate of glass or plastic material (for example polymethyl methacrylate) having the shape of a disk, card, etc. by a technique such as vapor deposition. For example, 5i02 J is placed above the formed optical recording layer in order to protect the layer from outside air conditions such as humidity, prevent deterioration of the characteristics of the recording medium, and eliminate deterioration over time.
A protective film made of a metal oxide such as ^z203 can be deposited by a technique such as vapor deposition.

〔Example〕

The invention will now be described with reference to the following examples.

Example 1: An acrylic resin disc with a diameter of 30c+a was prepared and thoroughly washed. This disk was set in a vacuum deposition machine, and a thin film of 5i02 was vapor-deposited with a thickness of 300 while the disk was rotating. In place of the 5i02 thin film used in this example, transparent thin films of various oxides, fluorides, nitrides, etc. could also be used.

The materials described below were then simultaneously deposited from the three deposition sources using the same vacuum deposition machine.

Second evaporation source Selenium (Se) Third evaporation source Ge-Sn alloy (Ge:Sn=3:
1) The evaporation speed of each evaporation source was adjusted such that the volume ratio of VO-Pc in the deposited thin film was 40%, and the atomic ratio of Se, Ge, and Sn in the remaining inorganic material was 60% each.
%.

They were adjusted to 30% and 10%, respectively.

A single optical recording layer (thickness: 1000 nm) consisting of VO-Pc, Se, Ge and Sn was formed.

Next, on the optical recording layer formed as described above, a 5i02 film was deposited as a protective film to a thickness of 500 ml. Note that in place of this Si02 protective film, it was also possible to use the various transparent thin films listed above or a transparent polymer thin film such as polymethyl methacrylate.

On the disk with the optical recording layer that has been processed as described above,
While rotating it at 180Orpm, the wavelength was 830n.
m focused beam of semiconductor laser light (beam diameter 0.8 μm
) was irradiated. Next, in order to compare the reflectance of the laser beam irradiated part with that of the non-irradiated part, the irradiation power was set to 10n.
When the entire surface of the disk was irradiated with +H pulsed light (5 MIIz), a significant increase in reflectance was confirmed in the portions that were previously irradiated with laser light.

From this result, it can be seen that although the thin film of the optical recording layer was in an amorphous state immediately after vapor deposition, it changed to a highly crystalline state by irradiation with semiconductor laser light. Furthermore, when this crystalline optical recording layer was irradiated with high-intensity short pulse light, it changed again to a state with low reflectance, that is, an amorphous state. This means that in this optical recording layer, it is possible not only to write information but also to erase information.

Furthermore, the above method is applied to Ge-Sn, which is a third thin deposition source.
Even when the alloy was omitted, satisfactory results similar to those described above were obtained.

The procedure described in Example 1 above was repeated for ±. However, in the case of this example, vapor deposition is not performed simultaneously from three vapor deposition sources, but from the first... A three-layer optical recording layer was formed by sequentially using the second and third deposition sources. The thickness of the VO-Pc film is 300 people,
The thickness of the Se film was 400 mm, and the thickness of the Ge-Sn film was 200 mm.

The disc of the obtained multilayer optical recording layer material was irradiated with semiconductor laser light and pulsed light in the same manner as in Example 1, and the change in reflectance of the light irradiated portion was measured. As in Example 1, it was confirmed that the reflectance increased in the laser beam irradiated area and that the reflectance decreased due to the irradiation with high-intensity short pulse light.

The procedure described in Example 1 above was repeated on ±1. However, in the case of this example, the film thickness of 5i02 on the disk was 200, and the following three evaporation sources were used.

First vapor deposition source vO-Pc Second vapor deposition source Tellurium (Te) Third vapor deposition m, Ge-Sn alloy (Ge:Sn=2
:l) In this example, the volume ratio of VO-Pc in the deposited thin film is 50%, and of the remaining inorganic material, Te,
The evaporation speed of each evaporation source was adjusted so that the atomic ratios of Ge and Sn were 70%, 20%, and 10%, respectively.

Furthermore, in this example, the film thickness of 5i02 as a protective film is 1
The number of people was 500.

The disc of the obtained optical recording layer material was irradiated with semiconductor laser light and pulsed light in the same manner as in Example 1, and the change in reflectance of the light irradiated portion was measured. As in Example 1, it was confirmed that the reflectance increased in the laser beam irradiated area and that the reflectance decreased due to the irradiation with high-intensity short pulse light.

Furthermore, the above method is applied to Ge-Sn, which is a third evaporation source.
Even when the alloy was omitted, satisfactory results similar to those described above were obtained.

Comparison ■± For comparison, the procedure described in Examples 1, 2 and 3 above was repeated in the absence of vanadium phthalocyanine. However, the table shows that in all cases, the sensitivity of the optical recording layer to semiconductor laser light is poor, and almost all
Only by applying twice the irradiation power could the crystal state be changed.

Furthermore, the optical recording layer itself was not stable, and partial crystallization was observed even immediately after its deposition.

〔Effect of the invention〕

According to the present invention, it is possible to obtain a highly sensitive optical recording layer that can record information to a satisfactory degree even with a small and low-output semiconductor laser, and this optical recording layer can be used to perform various useful purposes. Optical recording materials can be produced. Further, according to the present invention, since a small semiconductor laser can be used, the device can be made smaller and lower in price.

Claims (1)

[Claims] 1. An optical recording layer of a type that records information by a change in the state of the irradiated part caused by irradiation with a low-output semiconductor laser beam, which is made solely of a metal of Group 6B of the periodic table. or a recording medium consisting of a combination of 50% or more of a metal from group 6B of the periodic table and less than 50% of a metal from the same group and/or a different group, and an organic material capable of increasing the sensitivity of the recording medium to the laser light. 1. An optical recording layer for low output semiconductor laser light, comprising a dye. 2. The optical recording layer according to claim 1, which consists of a single layer. 3. The optical recording layer according to claim 1, which is composed of multiple layers and in which the recording medium layer and the organic dye layer are alternately laminated. 4. The optical recording layer according to any one of claims 1 to 3, wherein the recording medium is made only of selenium. 5. The recording medium consists of a combination of 50% or more selenium and less than 50% at least one of tellurium, sulfur, germanium, antimony, bismuth, tin, lead, silicon, gallium, aluminum, indium, or zinc. , an optical recording layer according to any one of claims 1 to 3. 6. The optical recording layer according to claim 4 or 5, wherein the organic dye is 50% or less in volume percentage. 7. The optical recording layer according to claim 6, wherein the organic dye is a phthalocyanine dye. 8. The optical recording layer according to any one of claims 1 to 3, wherein the recording medium is made only of tellurium. 9. The recording medium consists of a combination of 50% or more tellurium and less than 50% at least one of selenium, sulfur, germanium, antimony, bismuth, tin, lead, silicon, gallium, aluminum, indium, or zinc. , an optical recording layer according to any one of claims 1 to 3. 10. The organic dye is 80% or less in volume percentage,
The optical recording layer according to claim 8 or 9. 11. The optical recording layer according to claim 10, wherein the organic dye is a phthalocyanine dye.