JPS59225992A - Optical recording medium - Google Patents

Abstract

PURPOSE:To obtain an optical recording medium high in sensitivity, showing an extremely high S/N ratio of reproduced signals, stable and having low toxicity, by using a composite layer comprising particulates of a specified metal or a semiconductor dispersed therein and a recording layer consisting of a specified semiconductor. CONSTITUTION:The composite layer 1 comprising particulates of a metal or a semiconductor dispersed in a metallic oxide is provided on a base 3, and a semiconductor layer 2 is provided on the surface thereof. An energy beam incident on the optical recording medium is absorbed into the semiconductor layer and the composite layer, the resultant heat melts the composite layer, and recording and reproduction are performed by utilizing the change in the optical property (reflectance, transmittance or the like) of the part irradiated with the energy beam. Examples of the metal or semiconductor used for the composite layer include Sn, In, Sb, Pb, Al, Zn, Cu, Ag, Au, Ge and alloys comprising one of them as a main constituent. Examples of the metallic oxide include oxides of Sn, In, Al, Zr and Zn. When Ge is used for the semiconductor layer, a recording medium having high sensitivity and showing a high S/N ratio of reproduced signals can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to changes in reflectance or transmittance that occur when the energy ray irradiated portion of the n layer is deformed or removed by melting or the like by irradiating energy rays such as laser light. The present invention relates to a recording medium suitable for optically recording and reproducing information using.

The properties required for optical recording media such as optical discs are as follows:
These include high recording sensitivity in the wavelength range of the laser used as the recording light source, high signal-to-noise ratio of the reproduced signal, high recording density, excellent storage stability, and low toxicity.

In so-called heat mode recording media, the recording layer melts due to the temperature rise of the laser beam irradiation area and forms bits.
In order to increase the recording sensitivity, it is necessary that the recording layer has a high spectral absorption rate, a low melting point, a low specific heat, and a low thermal conductivity, and it is desirable that the nWs be thin. In order to achieve a high signal-to-noise ratio of the reproduced signal, the bits must be of the same shape and size, and there must be no disturbance around the bits, and if reflected light is used for reproduction, the recorded and unrecorded areas must be In addition, in order to increase the recording density, low thermal conductivity is required.Also, in order to obtain a recording medium with excellent storage stability, oxidation of the recording layer is required. High stability and moisture resistance are required.

The currently available recording medium for lasers is one in which a thin film of tellurium or a tellurium alloy such as a tellurium-arsenic alloy is formed as a recording layer on a glass or plastic substrate. Tellurium and tellurium alloy RH are
It has high light absorption rate in the visible to near infrared wavelength range, low thermal conductivity, and low melting point, so it has high recording sensitivity, and the bit shape and size are easy to match, and it is suitable for the visible to near infrared wavelength range. Since it has an appropriate reflectance, it has properties that are extremely suitable for heat-mode laser recording media, such as the ability to obtain a reproduced signal with a high signal-to-noise ratio using reflected light. However, tellurium mM and tellurium-arsenic alloy thin films have drawbacks such as low oxidation stability and high toxicity. Attempts have been made to improve the oxidation stability by adding selenium to tellurium or tellurium-arsenic alloys, or by using low tellurium oxides, but so far no satisfactory results have been obtained, and the toxicity No effective measures have been found for this.

In terms of toxicity, one advantage over tellurium-based recording media is the use of a dye or a layer in which the dye is dispersed in a polymer on a glass or plus deck substrate, or on a reflective layer such as aluminum provided on the substrate. There is a recording medium that has been formed.

However, the absorption wavelength of dyes is generally on the shorter wavelength side than red light, and is in the oscillation wavelength range of 750 nm to 85 nm, which is the oscillation wavelength range of semiconductor lasers, which are expected to become the mainstream of recording light sources in the future.
Since a stable dye that exhibits large absorption in the 0 nm region cannot be obtained, a practical dye-based recording medium using a semiconductor laser as a recording light source has not been obtained.

The present inventors have developed a composite layer in which fine semiconductor particles having low toxicity, oxidation stability, and water resistance are dispersed in a metal oxide thin film with excellent chemical stability, and a surface of at least one of the composite layers. The present inventors have discovered that by using a recording layer made of a specific semiconductor in contact with an optical recording medium, it is possible to obtain an optical recording medium that is highly sensitive, has an extremely high signal-to-noise ratio of a read signal, is stable, and has low toxicity, and has arrived at the present invention.

The gist of the present invention is to provide, on a substrate, a composite layer in which metal or semiconductor fine particles are dispersed in a metal oxide thin film, and a recording layer consisting of a semiconductor layer in contact with one surface of the composite layer. The structure and structure of an optical recording medium is characterized in that:

FIG. 1 shows an example of the layer structure of the optical recording medium of the present invention.

In Figure 1, a composite layer (hereinafter referred to as a composite layer) in which metal or semiconductor fine particles are dispersed in a metal oxide is provided on a substrate, and a semiconductor layer is formed on the surface of the composite layer. has been done. In this optical recording medium, the energy rays incident from the substrate side or the side opposite to the substrate are absorbed by the semiconductor layer and the composite layer, and the generated heat melts the composite layer, and the melted portion of the composite layer is transferred to the semiconductor layer. Recording and reproduction are performed by utilizing changes in optical properties such as reflectance and transmittance of the part of the medium that is irradiated with energy rays, which is generated by bits that are formed by moving the part in contact with the bit. will be held.

Examples of metals or semiconductors used in the composite layer in the optical recording medium of the present invention include Sn, In, Pb,
lXZn5 Cu54L^us sb,,[11,,S
Examples of preferred metals or semiconductors from the viewpoint of low toxicity include Sn, In, Sb, pb, ^1,
Examples include Zn-, C11%88, Heu1Ge, and alloys containing these as main components. The characteristics of the metals or semiconductors mentioned above include high reflectance in the oscillation wavelength range of semiconductor lasers, low melting points, low toxicity, and high stability in air. When using an alloy that has the following properties, care must be taken to ensure that the above characteristics are not lost.

The metal oxide used in the composite layer in the optical recording medium of the present invention must have excellent chemical stability and low thermal conductivity. Preferred examples include Sn, In, and In.
, ^1. Examples include oxides of Zr and Zn, and in particular, use of oxides of Sn or In provides a recording medium with excellent stability in air, high sensitivity, and a high signal-to-noise ratio of reproduced signals. Examples of oxides of Sn or In include the chemical formulas 5nOx, In, oj and 5nOz-x, rna
Low oxides such as OJ-x, Sn+-yMyoa, In
Examples include 5nOa such as z-zNzoj, and In 2oj doped with a different metal. Here xSz
is 0.5 or less, y is a positive number of 0.25 or less, M is Sb,
, In.

N represents a metal such as Sns, Ges, Pbs, Zn, etc.

The filling rate of metal or semiconductor in the above composite layer is 0.
It needs to be 3 or more and 0.95 or less. If the filling factor is less than 0.3, the absorption coefficient of the composite layer decreases, and the temperature at which the composite layer melts and fluidizes increases, resulting in a decrease in the recording sensitivity of the resulting optical recording medium. When the filling factor becomes 0.95 or more, contact between the metal or semiconductor particles dispersed in the composite layer begins, and the particle size of the metal or semiconductor particles increases, resulting in irregularities in the size and shape of the recording bits. , the S/N ratio of the reproduced signal decreases, and the thermal conductivity of the composite layer also increases, resulting in a decrease in recording sensitivity.

The thickness of one layer of the composite layer in the optical recording medium of the present invention is 10
It is desirable that the thickness is Å or more and 500 Å or less. If the thickness of one layer of the composite layer is less than 10 Å, it becomes difficult to form bits in the semiconductor layer by melting and fluidizing the energy ray irradiated portion of the composite layer, and the recording sensitivity of the recording medium decreases. Furthermore, if the thickness of one layer of the composite layer is 500 Å or more, the energy required to melt and fluidize the energy ray irradiated portion of the composite layer increases, resulting in a decrease in the recording sensitivity of the recording medium. In particular, when the thickness of one layer of the composite layer is 30 Å or more and 300 Å or less, a recording medium with high sensitivity and a high signal-to-noise ratio of reproduced signals can be obtained.

Examples of the semiconductor layer used in the optical recording medium of the present invention include elemental semiconductors such as Ge, St, Se, and ISb.
, GaAs, , GaSb, InP.

Examples include compound semiconductors such as 1nAss InSb.

Especially when Ge is used for semiconductors, it is homogeneous and T50nm.
Since a layer having a large light absorption coefficient in the wavelength range of ~850 nm can be obtained, a recording medium with high sensitivity and a high signal-to-noise ratio of reproduced signals can be obtained. Furthermore, Ge1l has excellent oxidation stability and moisture resistance even in the form of a thin film, and is also low in toxicity, making it suitable as the semiconductor layer used in the optical recording medium of the present invention. Further, in the optical recording medium of the present invention, a semiconductor layer made of a thin film of Ge doped with Ga, In, sb, or the like can also be used.

The thickness of one layer of the semiconductor layer in the optical recording medium of the present invention is 1
It is desirable that the current is 0 A or more and 200 Å or less. When the thickness of one layer of the semiconductor layer is 10 Å or less, the resulting recording medium has a thickness of 750 Å.
The reflectance and absorption rate of light in the wavelength range from r+m to 850 nm decrease, the contrast between the recorded portion and the unrecorded portion cannot be increased, and the SN ratio of the reproduced signal decreases. If the thickness of one layer of the semiconductor layer is 200 Å or more, even if the energy ray irradiated portion of the composite layer is melted and fluidized, it becomes difficult for the semiconductor layer to form a focus, resulting in a decrease in the recording sensitivity of the recording medium.

In particular, when the thickness of one layer of the semiconductor layer is 20 Å or more and 100 Å or less, the recording medium has a high S/N ratio.One embodiment of the optical recording medium of the present invention is to form a composite layer on a substrate, and furthermore, to form a composite layer on the surface of the composite layer. A semiconductor layer is formed on the substrate. The substrate may be a metal plate such as aluminum, a glass plate, or polymethyl methacrylate, polystyrene, polyvinyl chloride, polycarbonate, polyethylene terephthalate,
Sheets or films of thermoplastic or thermosetting resins such as polybutylene terephthalate, polyamide and epoxy resins, diallyl phthalate polymers, diethylene glycol bisallyl carbonate polymers, polyphenylene sulfide, polyphenylene oxide, and polyimide are used. In particular, when the optical recording medium of the present invention is used as an optical disc in which recording light and reproduction light are irradiated through a substrate, the substrate may be made of methyl methacrylate polymer, styrene polymer, polyvinyl chloride, polycarbonate, It is necessary to use a sheet of transparent plastic such as diethylene glycol bisallyl carbonate polymer or epoxy resin. Furthermore, when using a glass plate or a metal plate such as aluminum as a substrate, a highly sensitive optical recording medium can be obtained by forming a single layer of polymer on these substrates and then forming a recording layer consisting of a composite layer and a semiconductor layer. It will be done. Examples of the above polymers include polystyrene, polymethyl methacrylate, polyisobutyl methacrylate, and the like.

Examples of the layer structure of the optical recording medium of the present invention are shown in FIGS. 2 to 5. The method for manufacturing a recording medium of the present invention will be explained below using an example diagram of a layer structure.

In the recording medium having the configuration shown in FIG.
After repeating this operation, a semiconductor main layer is formed as the outermost layer, thereby stacking n semiconductor layers and n-1 composite layers. ). In order to form the semiconductor layer and the composite layer, for number=1, a vacuum deposition method, an ionization deposition method, an ion blating method, a sputtering method, a cluster ion beam method, etc. are used. (When forming a cover layer,
A metal or a semiconductor metal oxide is placed in a separate crucible, and vapor deposition is performed by simultaneously evaporating the metal or semiconductor metal oxide in a vacuum of less than I x 10' mHg. Further, it is also possible to use an ionization deposition method in which evaporated particles are ionized in the vacuum deposition process and collide with the semiconductor layer surface, or an ion blating method in which ionized particles are accelerated by applying a DC voltage on the substrate side at the same time as ionization. . Also, metal or semiconductor targets.
Simultaneous S/N using a metal oxide target throat)
A composite layer can also be formed by adding one ivy. In either case, when forming a composite layer, a sensor head such as a crystal film thickness sensor is installed relatively close to each evaporation source and target, and the evaporation rate and sputtering rate of the metal or semiconductor and metal oxide can be adjusted separately. By sensing and controlling, a composite layer with a predetermined metal or semiconductor filling rate and thickness can be obtained.

A recording medium having the configuration shown in FIG. 3 has a composite layer 1 on a substrate 3.
After forming the semiconductor layer 2 on the composite layer 1, this operation is repeated to form the composite layer n.
It is obtained by laminating n layers of semiconductor layers.

A recording medium having the configuration shown in Figure m4 is produced by laminating n layers of semiconductor layers 2 and n layers of composite layer 1 on a substrate 3 by performing the same operation as in the case of manufacturing a recording medium having a configuration not shown in Figure 2. obtained by letting The recording medium having the configuration shown in FIG.
The same operation as in the case of manufacturing the recording medium having the configuration shown in the figure is performed, and n layers of the composite layer l are formed on the substrate 3, and n layers of the semiconductor layer 2 are formed on the substrate 3.
It is obtained by laminating one layer.

In the optical recording medium of the present invention having the configuration shown in FIGS. 2 to 5, the thickness of the recording layer (the total thickness of the composite layer and the semiconductor layer) is preferably 50 Å or more and 2000 Å or less. desirable. When the thickness of the recording layer becomes 2000 Å or more, the volume of the energy ray irradiated part of the recording layer becomes large, and the density of energy absorbed when irradiated with energy rays decreases, resulting in a decrease in the recording sensitivity of the recording medium. Furthermore, the shape of the formed periphery of the VISO becomes more likely to be disturbed, which adversely affects the S/N ratio of the reproduced signal. If the thickness of the recording layer is 50 Å or less, the difference in reflectance and transmittance between the recorded part and the unrecorded part of the recording medium will be small, and the contrast will be low.
It is not possible to increase the SN ratio of the reproduced signal. When the optical recording medium of the present invention is used in a reflective optical disc, a more preferable thickness range of the recording layer is 70 Å or more and 500 Å or less.

In the optical recording medium of the present invention having a structure not shown in FIGS. As long as the thickness of the recording layer in which the semiconductor layer and the semiconductor layer are laminated is within the range of 50 to 2000 layers, the value of n may be any integer of 1 or more. In particular, when Ge is used in the semiconductor layer and n is 2 or more in the configuration shown in FIG. 2, an optical recording medium with particularly excellent stability in air and moisture resistance can be obtained.

The recording layer in the optical recording medium of the present invention is extremely stable under normal environments, and there is no need to provide a protective layer, but protection against mechanical shock and adhesion of dust etc.
In order to prevent problems with recording and playback,
It is possible to provide a protective layer on top of the recording layer. As the protective layer, inorganic materials and organic polymer materials such as Stow, Al-107, and TiO2 are used.

In the optical recording medium of the present invention shown in FIGS. 2 to 5, when the curtain plate 3 is made transparent, even if the recording light and the reproduction light are incident from above in the drawings, they are not incident from below. You can let me.

The optical recording medium of the present invention is characterized by low toxicity, high sensitivity, excellent stability in air and moisture resistance, and an extremely high S/N ratio of the reproduced signal. The reason why the optical recording medium of the present invention exhibits the above-mentioned (excellent characteristics) is not necessarily clear at present, but it can be estimated as follows. Since the recording layer is composed of a laminated film of a composite layer and a semiconductor layer with different values, energy rays can be absorbed even when the thickness of the recording layer is extremely small compared to when the recording layer is composed of a composite layer or a semiconductor layer alone. Absorption rate and reflectance increase.For this reason, the energy density in the area of the recording layer that is irradiated with energy rays increases, and at the same time, the recording sensitivity increases, and at the same time, the contrast between the recorded area and the unrecorded area increases. The signal-to-noise ratio during reproduction is increased.Furthermore, the composite layer constituting the recording layer is made of a metal oxide and extremely fine metal or semiconductor particles dispersed in this oxide, the particle size of which is less than the wavelength of light. As a result, it easily fluidizes with the adjacent semiconductor layer at a lower temperature than the bulk metal or semiconductor.The fluidized portion of this recording layer is The fluidized recording layer has a large surface energy, and the difference in surface energy between the fluidized recording layer and the surface of the substrate that comes into contact with it becomes large, and the fluidized recording layer moves smoothly.
Bit formation becomes easier. This movement of the fluidized recording layer is thought to occur due to the difference in surface energy between the fluidized portion and the surrounding phase (Japanese Patent Laid-Open No. 55
In the optical recording medium of the present invention, the semiconductor layer tends to have an amorphous or microcrystalline structure, and since the metal or semiconductor particles in the composite layer are extremely small, the size and shape of the bits do not change. It is thought that it will have a big impact, and moreover, it is common metal Il! The influence of grain boundaries caused by large crystals often seen in I films is eliminated. As a result, it is thought that bits with uniform shape and size and little disturbance in the peripheral area are formed with low irradiation energy.

Furthermore, the semiconductor layer constituting the recording layer in the optical recording medium of the present invention has a low thermal conductivity, and the metal or semiconductor fine particles exist isolated from each other in the oxide in the composite layer. The thermal conductivity of the recording medium also decreases, and the sensitivity of the recording medium increases. Furthermore, by appropriately selecting the metal filling rate in the composite layer, the semiconductor layer, and the thickness of the composite layer, a recording medium with optimal spectral absorption and reflectance can be obtained.

The metals, semiconductors, metal oxides, etc. used in the recording layer of the optical recording medium of the present invention are all extremely stable in air and water, and have low toxicity, so the optical recording medium of the present invention can be stored with low toxicity. It also has excellent stability.

The optical recording medium of the present invention can be used not only as an optical disk for recording and reproduction, but also as an external memory for a computer, a document file, a data file, and a computer.
It can be used as tapes, cards, microfiche, etc. that can be directly written and read with laser light.

Hereinafter, the details of the present invention will be illustrated by examples, but the present invention is not limited to these examples.

Note that the filling rate shown in the following examples is the volume ratio occupied by metal or semiconductor fine particles in the composite layer.

Example 1 A disk-shaped substrate made of polymethyl methacrylate with a thickness of 1.2 mm, an outer diameter of 300 mm, and an inner diameter of 351 mm was attached to the chamber of a vacuum evaporation apparatus, and each of three crucibles was filled with Ge (manufactured by Furuuchi Chemical Co., Ltd., 30φ m t,
purity 99.999%), sn (manufactured by Furuuchi Chemical, 30φ
X10mt, purity! 'J 9.99%), 5nOz (
Made by Furuuchi Chemical, 18φX 5 x m t, purity 99
．． 99%), and while rotating this substrate at a speed of 2 Orpm, Ge was first evaporated to a thickness of 30 mm using electron beam evaporation under vacuum conditions of I x 10-6 W Hg. Next, Sn and 5nOz were irradiated with electron beams from separate electron guns, and vapor deposition was performed while controlling the evaporation rate of Sn and SnO2 to obtain a film thickness of 60 nm with a Sn filling rate of 0.8. By forming a composite layer on the Ge layer and subsequently performing the same operation, a 20-thick Ge layer and a 60-thick Sn and SnO2 composite layer are formed on this Sn and SnO composite layer. A disk-shaped optical recording medium having a recording layer with a thickness of 200 layers and a configuration corresponding to n=3 in FIG. 2 was manufactured by sequentially laminating GeJi layers with a thickness of 30 layers.

While rotating the obtained disc-shaped optical recording medium at a rotational speed of 1800 revolutions per minute, it was repeatedly rotated at a frequency of 5M1lz.
Semiconductor laser modulated to 100 nsec pulse 11 (Hitachi rupture+1LP-1600, oscillation wavelength 830 nm)
When recording was carried out by irradiating the recording layer with oscillated light (nm) to a beam diameter of 1 μm through a collimator lens, condensing lens, and substrate, the short axis was approximately 1 μm.
The laser beam intensity on the recording surface of the disk required to form the bits was 6IIIW. In addition, the recorded signal is reproduced with a 1 mW laser beam, and a reference signal of 5 Ml
The CN ratio measured with a spectrum analyzer under the conditions of 1z, band rlJ 100 K11z was 56 dB.

The recorded disc-shaped recording medium, on which the recording was performed as described in Section 2 above, was placed in a constant temperature and humidity layer at 60°C and 95% RH, and was heated for 12 hours.
When a 0-day moist heat resistance test was conducted, no change was observed in the CN ratio.

Three disk-shaped substrates made of polymethyl methacrylate similar to those used in Example 1 were prepared, and as in Example 1, the substrate rotation speed was 2 Orpm and the degree of vacuum was I x 10-6n+.
In 11g, Sn and SnO2 were co-evaporated onto these substrates using an electron beam evaporation method while controlling the evaporation rate, and the Sn filling rate was 0.8 and the film thickness was 100 nm and 180 nm, respectively. 5nliik in humans and 300 SnO,L
Three types of samples were obtained, each having only a composite layer in which particles were dispersed.

Table 1 shows the results of recording and reproducing the three types of samples obtained in the same manner as in Example 1.

Table 1 1) Comparative example 2 of laser light intensity on the disk surface necessary to form a bit with a short diameter of 1 μm A disk-shaped substrate of polymethyl methacrylate similar to that used in Example 1 was used. Two substrates were prepared, and the substrate rotation speed was 20 rpm and the vacuum degree was I x 10-'mt in the same manner as in Example 1.
Ge was deposited on these substrates using an electron beam evaporation method under the conditions of 1g to obtain two types of samples, one with a Ge film thickness of 80 and one with a Ge thickness of 300.

An attempt was made to record the obtained two types of samples under the same conditions as in Example 1, but no bits were formed in any of the samples at a laser light intensity of 12 m11, and recording was not possible.

As is clear from Example I and Comparative Examples 1 and 2, Comparative Example 1
The sample in which the recording layer is made only of a composite yJ film of Sn and SnO2 has lower sensitivity and CN ratio than the optical recording medium of the present invention shown in Example 1, and the comparison in which the recording layer is made only of a GeFW film is lower. The sample shown in Example 2 has significantly lower sensitivity than the optical recording medium of the invention.

Example 2 Using the same method as in Example 1, a composite layer consisting of the metals and metal oxides shown in Table 2 and having the film thickness shown in Table 2 was formed on a disc-shaped substrate of polymethyl methacrylate. , not shown in Table 2! A semiconductor layer made of Ge of IIF\,
By forming recording layers laminated in the layer configuration shown in Table 2, 13
We have produced various types of optical recording media.

The recording sensitivity and C of the obtained 13 types of disc-shaped optical recording media were measured using the same method as in Example 1.
The N ratio is shown in Table 2. Moisture resistance showed particularly excellent results when n was 2 or more.

Example 3 A film with a thickness of 1.2 m11. A disk-shaped substrate made of diethylene glycol bisallyl carbonate polymer (product name CR-39) with an outer diameter of 300 mm and an inner diameter of 35 mm was attached, and Ge, ..., Sn were placed in each of the four crucibles in the chamber.
s Au and SnO2 are added, and the above substrate is heated to 2 Orpm.
While rotating at a rotational speed of
■-] Under the conditions of glazing, Go was first vapor-deposited to a thickness of 50 mm, and then 8 holes, sieves, and SnO were each irradiated with electron beams from separate electron guns to form Sns Au and SnO2. By simultaneously depositing the three components while adjusting the evaporation rate, Sn-U alloy particles consisting of 90% Sn and 10% sieves are dispersed in SnO,
The filling rate of alloy fine particles was 0.7 to form a composite layer with a thickness of 150 mm, and then G was deposited on the composite layer again to a thickness of 50 mm.
A disk-shaped optical recording medium having a recording layer having a thickness of 250 mm and having a configuration corresponding to n='l in FIG.

The recording and reproducing characteristics of the obtained optical recording medium measured in the same manner as in Example 1 are shown in Sample No. 3-1 in Table 3.

In addition, the optical recording media of sample numbers 3-2 to 3-6 shown in Table 3 were manufactured in the same manner as sample number 3-1, and the types and alloy compositions of the alloys in the composite layer were as shown in Table 3. Other than that, the substrate, the type and thickness of the semiconductor layer, the filling rate of alloy fine particles in the composite layer, the thickness of the composite layer, the configuration of the recording layer, and the thickness of the recording layer are all the same as those of sample number 3-1. It is the same as the case. Table 3 shows the recording and reproducing characteristics measured under the same conditions as in Example 1 for the optical recording media of sample numbers 3-2 to 3-6.

The stability and moisture resistance were measured in the same manner as in Example 1 and were found to be good.

Table 3

[Brief explanation of the drawing]

1, 2, 3, 4, and 5 are cross-sectional views of the optical recording medium of the present invention. In each figure, 1 is a composite layer, 2 is a semiconductor layer, and 3 is a substrate. Agent Patent Attorney Katsutoshi Takahashi 2 '3 2 \1 1 2 1 1/2 3 I 2 2

Claims (1)

[Claims] 1. A recording layer consisting of a composite layer in which metal or semiconductor fine particles are dispersed in a metal oxide thin film and a semiconductor layer in contact with at least one surface of the composite layer is formed on a substrate. An optical recording medium characterized by: 2. The metal or semiconductor fine particles are Sn, In,
Sb, Pb. The optical recording medium according to claim 1, which is fine particles of 41% Zn, CL1, Ag, A11% Ge, or an alloy whose main component is any of these metals or semiconductors. 3. Metal oxides include Sn, In, AI, Zr and Zn
The optical recording medium according to claim 1, which is at least one kind selected from oxides of. 4. The optical recording medium according to claim 1, wherein the semiconductor layer is GeWA.