JPH0473187A - Optical recording medium - Google Patents

Abstract

PURPOSE:To enable information to be recorded, regenerated and erased by providing a recording material layer made up of a specific composition on a base plate. CONSTITUTION:The recording material layer reversibly changeable in phase by lighting, heating or other means is provided on a base plate and, by using changes in optical property accompanied by the phase change, the information is recorded, regenerated or erased. This recording material layer is made up of the composition shown in the formula I. At this time, a 100nm thick base plate protective layer 2 made of SiO2, a 100nm thick recording material layer 3 made of [GaSb85Sb2Te315)]65Sb35, a 100nm thick protective layer 4 made of SiO2 and a 200nm thick heat dissipating layer 5 made of aluminum alloy are built up in layers successively on a 1.2mm thick acrylic base plate 1 by an RF magnetron spattering method. Moreover, a 1.2mm thick acrylic protective plate 7 is layered on the heat dissipating layer 5 via an adhesive layer 6 of ultraviolet hardening resin to form an optical recording medium.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention irradiates a recording material layer with a light beam such as a laser beam to change the optical properties of the irradiated area, and changes the optical properties. Use it to record and reproduce information, or to record and reproduce information.
It relates to rewritable optical recording media that can be read and erased, and in particular can write or rewrite information at high speed, retain this recorded information for a long period of time, and improve recording sensitivity and repeated rewriting durability. This invention relates to improvements to optical recording media that can achieve this.

[Conventional technology]

2. Description of the Related Art Conventionally, magneto-optical recording media have been used as rewritable optical recording media on which information is recorded using a light beam such as a laser beam, and have been put into practical use in some cases. In other words, this method applies optical energy and a magnetic field to write information by reversing the magnetization direction of the recording material layer, while detecting the difference in Faraday rotation angle or Kerr rotation angle depending on the magnetization direction to obtain a reproduction signal. It is a method.

However, this method has been applied only to limited fields because there is no practical method for rewriting at least one sector.

On the other hand, as another rewritable optical recording medium, a so-called phase-change optical recording medium that utilizes a phase change between crystal and amorphous is currently under research.

That is, in this method, as shown in FIG. 4, a part of the recording material layer (a) in a crystalline state (CR) is irradiated with a high-power laser beam, and the recording material layer (a) in that region is irradiated with a high-power laser beam. After melting, it is rapidly cooled to change it to an amorphous state (am), which usually corresponds to the recorded state.However, when erasing, as shown in Figure 5, the recorded area is irradiated with a low-power laser beam to melt the After that, it is slowly cooled to form a crystalline state (
cr).

In this method, two light beams are used to
In addition to being able to rewrite within one sector (i.e., erasing the recorded information with the preceding beam and then recording with the next light beam), if a recording material with a short crystallization time is used, one sector can be rewritten. Since it is possible to override with a light beam (that is, to simultaneously rewrite information that is recorded or erased while selectively switching the beam output), it has the advantage of being applicable in various fields.

By the way, from the viewpoint of simplifying the optical system or improving the transfer speed, it is preferable that the recording material used in this phase change type optical recording medium has a short crystallization time.
In addition, from the viewpoint of retaining recorded information over a long period of time, it is preferable that the stability in the amorphous phase is high (usually evaluated by the crystallization temperature of the recording material), and the crystallization time is 100 ns or less. , preferably 50 ns or less, while the crystallization temperature was said to be at least 140° C. or higher.

As a material that satisfies these two requirements, [IEICE CPM87-88: 19B?] ] and JP-A-63-2
No. 25934 discloses a Ge-5b-Te ternary recording material. In other words, although this ternary recording material has a short crystallization time (30 ns), the stability of the amorphous phase is not sufficient (crystallization temperature: 100°C).
Sb! 'tel, the stability of the amorphous phase is sufficient (crystallization temperature: 200 °C), but the crystallization time is long (1
00ns or more) GeTe, and was said to have intermediate properties between the above-mentioned Sb2Te+ and GeTe.

However, as mentioned above, this GeTe has a long crystallization time < (100 ns or more), and the higher the mixing ratio, the longer the crystallization time of Ge-3b-Te. G of the composition to ensure the temperature of
Since the crystallization time of e-3b-Te is 50 ns or more, although it is possible to put it into practical use, its characteristics are not sufficient.

On the other hand, as another recording material that satisfies the above two requirements, Ga-3b-T
A ternary recording material of e is mentioned.

That is, this Ga-3b-Te is [APPLIED
0PTIC5Vo 1.26. No. 22:
15/Nov, /' 87], the crystallization time is short < (20 ns) and the stability of the amorphous phase is high (crystallization temperature: 350°C). , Te which easily becomes amorphous
This is a recording material in which the amorphous state is improved by the addition of Ge-3b-Te, and, like the above-mentioned Ge-3b-Te, it is said to be a material that meets two requirements regarding crystallization time and stability of the amorphous phase.

[Problem to be solved by the invention]

By the way, in order to improve the amorphization of the GaSb, the Te is desirably 10at
It was necessary to add more than % (atomic %).

However, the proportion of Te in Ga-3b-Te is 10 at%
If the value exceeds the above, the crystallization time of the Ga-3b-Te becomes significantly longer (that is, the crystallization rate However, since the crystallization temperature of Te is as low as 10oC, as the proportion of Te increases, the crystallization temperature of Te increases.
There was a problem that the crystallization temperature of -3b-Te also decreased rapidly and the stability of its amorphous phase also deteriorated.

For this reason, like Ge-3b-Te, although it is possible to put it into practical use, its characteristics are still insufficient.

[Means to solve the problem]

The present invention has been made in view of the above problems, and its objective is to develop GaS, which has difficulty in becoming amorphous but has a short crystallization time and high amorphous phase stability.
b, and V b 2 VI, which has a short crystallization time, can be easily made amorphous, and has a higher crystallization temperature than Te.
By configuring the recording material with bh and Sb or Bi, which has the effect of inhibiting the phase separation phenomenon of mixed materials, information can be written or rewritten at high speed, and
It is an object of the present invention to provide an optical recording medium that can retain this recorded information for a long period of time and to improve the repeated rewriting resistance, and to provide an optical recording medium that can retain this recorded information for a long period of time and to improve the repeated rewriting resistance. , this G
The crystal structure is the same as that of aSb, and the optical band gap is Ga.
1nSb, which is smaller than rb; V b 2 VI b i, which has a short crystallization time and can be easily made amorphous, and has a crystallization temperature higher than Te; and Sb or By composing the recording material with Bi, information can be written or rewritten at high speed, this recorded information can be retained for a long period of time, and the recording sensitivity and repeated rewriting durability can be improved. The goal is to provide a medium.

In other words, the invention according to claim 1 is provided with a recording material layer on a substrate that undergoes a reversible phase change by means of light, heat, etc., and uses the change in optical properties accompanying this phase change to record and reproduce information. , or an optical recording medium for recording, reproducing, and erasing, and the above recording material is [(GaSb)too-, (M)t]too-g(N)
.

(However, M is a stoichiometric compound composed of Vb group elements and VIb group elements on the periodic table and whose chemical formula is expressed as Vb, VIbS, or a mixture of two or more of these stoichiometric compounds, while N is Sb or Bi, and the range of xXz is 7molX≦X≦95molX, 5molX≦2≦40molX, respectively. The invention according to claim 2 is provided with a recording material layer on a substrate that undergoes a reversible phase change by means of light, heat, etc., and records and reproduces information by utilizing changes in optical properties accompanying this phase change. , or an optical recording medium for recording, reproducing, and erasing, and the above recording material is ([(GaSb)too-y(InSb)y]ta0-
x(M)-] too-z(N)+ (where M is a stoichiometric compound composed of a Vb group element and a VIb group element on the periodic table and whose chemical formula is expressed as Vb2VIb, or its stoichiometric amount A mixture of two or more theoretical compounds, while N is Sb or Bi, and the ranges of X, y, and Z are respectively 5molX≦X≦85molX, 2molX≦y≦70molX, 5molX≦2≦40molX ) is characterized by being composed of the composition shown in

In such technical means, the above-mentioned Vb2VIb, in particular, Vb group elements such as As, Sb, and Bi, and 5SSe
It is composed of VIb group elements such as STe, and its chemical formula is Vb,
VIb.

Sb+Te+, BxtTe+, 5btSe expressed as
a, Bi+Ses, 5bxSs, Bi25+, AszS
There are stoichiometric compounds such as es and AStTes,
Also, a mixture of two or more of these equistoichiometric compounds,
For example, stoichiometric compounds such as BigSTet, other solid solutions, mixtures, etc. can be applied.

On the other hand, it is synthesized with GaSb, V b2VI b3, and Sb or Bi, and has the general formula [(GaSb) + oo
-x(M)t]too-+(N)+ includes the types of constituent elements of the above Vb2VIb, as well as G
Depending on the synthesis proportions of aSb, VLVIb+, and Sb or old, there are, for example, those that constitute stoichiometric compounds, those that constitute solid solutions, and those that constitute mixtures.

Furthermore, the synthesis ratio of Vb2VIbl, that is, the general formula [(caSb)too-, (M),] too-, (N
), when X≦7mo LX, the improvement of amorphization in GaSb is insufficient, and the above material [(GaSb)+Do-, (M),] l.

It becomes difficult to make o-, (N), amorphous, and on the other hand, in the case of X≧95 molX, [(GaSb)+. o-x(ML) l.o-, (
Since there is a risk that the crystallization rate of N) will slow down and the crystallization temperature will drop, resulting in deterioration of the stability of the amorphous phase, it is necessary to set it within the range of (7 molX≦X≦95 molX).

On the other hand, the synthesis ratio of Sb or Bi, that is, the general formula [(GaSb)1no-x(lit)x]too-+
The applicable range of Z in (N)z is that when Z≦5 mol (GaSb) too-x (M) iloo-x (N),
Since there is a risk that the repeated rewriting resistance of 2 will deteriorate again, it is necessary to set it within the range of (5 molX≦2≦40 molX).

Next, GaSb, InSb, Vb+VIbs, and Sb or Bi are synthesized, and the following general formula, ([(GaSb)too-, (InSb)y]too-
, (M), )too-+(N)+ includes the above-mentioned types of constituent elements of Vb and VIbl, as well as Ga
Depending on the synthesis ratio of Sb, InSb, Vb, VIb+, and Sb or Bi, there are, for example, those that constitute a stoichiometric compound, those that constitute a solid solution, and those that constitute a mixture.

In addition, the synthesis ratio of the above Vb2VIbs, that is, the general formula + [(GaSb)100-F(InSb)FIIOI-
! (M)! The applicable range of X in l 100-1(N)+ is that when X≦7molX, the improvement of amorphization in GaSb is insufficient, and
y(InSb)y] too-, (M), 1 100-,
(N) becomes difficult to amorphize. On the other hand, in the case of X≧85mo IX, [[(caSb
Loo-yNnSbLLoo-, (M), 1 too
-, (N), and there is a risk that the crystallization temperature will drop and the stability of the amorphous phase will deteriorate.
) must be set within the range.

In addition, the synthesis ratio of the above (InSb), that is, the general formula %
The applicable range of y in the formula % () is that when y≦2molX, the effect of the above-mentioned 1nSb that contributes to the improvement of recording sensitivity becomes insufficient, and when y≧70mol%, [[(GaSb)too -F(TnSb)ilQo-1
Since there is a risk that the crystallization rate of CM) j too-g(N)+ will be slow, (2mo] X≦y≦70
mol%).

On the other hand, the synthesis ratio of Sb or Bi, that is, [[
(GaSb)+on-y(InSb)y11o+-(M
) 81 The applicable range of Z in too-+(N)+ is that when Z≦5 mol In the case, [[(GaSb)loo-y(InSb)y]100-
, (M), 1 Since there is a risk that the repeated rewriting resistance of 1no-+(N)+ will deteriorate again, (5mo I
It is necessary to set it within the range of X≦2≦40molX).

In addition, the above [(GaSb)+ao-, (M)x}100-
, (N), and i[(caSb)100−y(+n
5b) In yLoo-, (M), 1 101-1 (N) I, the added Sb may act as crystal nuclei, and in this case, it has the effect of contributing to the improvement of recording sensitivity, and This has the effect of increasing the temperature at which the amorphous phase changes and further improving the stability of the amorphous phase.

Next, the basic structure of an optical recording medium to which the above-described recording material is applied is basically composed of a light-transmitting substrate and a recording material layer formed on this surface.

In addition, the purpose is to prevent the recording material layer from being deformed after melting and before it solidifies, or to prevent mechanical damage to the recording material layer.
It is also possible to provide a protective layer on the recording material layer for the purpose of preventing oxidation and the like.

In addition to glass, resin materials such as acrylic, polycarbonate, and epoxy can be used as the light-transmissive substrate. Here, if a resin material is used as the substrate,
To prevent thermal damage to the resin material, between the recording material layer and the substrate,
For example, a substrate protective layer made of SiO□, znSZrO2, or a mixture thereof may be provided. still,
In an optical recording medium in which recording, reproduction, and erasure are performed by irradiating a light beam from the opposite side of the substrate, the substrate may of course be made of a light-opaque material such as aluminum.

In addition, examples of the material constituting the protective layer include the same materials as those constituting the substrate protective layer, resin materials such as ultraviolet curing resin, acrylic, polycarbonate, and epoxy, and glass. . Further, the protective layer may be composed of a single layer of these materials, or may be composed of a plurality of laminated layers of the above materials. In addition, for the purpose of increasing the cooling rate, Au, AI
, a thermal diffusion layer made of a metal with high thermal conductivity such as Ag, or S
i, Ge, GaAs, BeO, AIN, TiC
, Cr, Fe, Rh, Be, Ir, or the like may be provided with a heat conduction control layer made of a material whose thermal conductivity decreases as the temperature increases.

Furthermore, as a method for forming the recording material layer, a sputtering method or a vacuum evaporation method can be used. In other words, the sputtering method described above includes simultaneous sputtering, in which a target composition is synthesized by using multiple targets and the amount of power applied to each target is appropriately adjusted, and the composition is deposited on a substrate at the same time. It is also possible to perform sputtering using one alloy target corresponding to the object. Further, as the above-mentioned vacuum evaporation method, a co-evaporation method can be used in which a target composition is obtained by using a plurality of evaporation sources and adjusting the respective evaporation rates, and simultaneously deposits the same on the substrate.

In the optical recording medium of this technical means, the amorphous phase of the recording material layer may correspond to the recorded state and the crystalline phase thereof may correspond to the erased state, as in the conventional case. The amorphous phase may correspond to the erased state and the crystalline phase may correspond to the recorded state, and the selection is arbitrary.

[Effect]

According to the invention according to claim 1, although the recording material has difficulty in becoming amorphous, the crystallization time is short (
20ns), and the stability of the amorphous phase is high (crystallization temperature = 350°C).
The following general formula, [(GaSb)too-, (M)i+oo-g(,N), synthesized with higher Vb2vrb and Sb or Bil, which has the effect of inhibiting the phase separation phenomenon of mixed materials.
Since it is composed of a composition represented by (This makes it possible to prevent segregation of the material. On the other hand, according to the invention of claim 2, the recording material has a short crystallization time, although it is difficult to become amorphous.
20ns), and the stability of the amorphous phase is also high (crystallization temperature: 350°C).The crystal structure is the same as that of GaSb (zincblende structure), and the optical band gap is higher than that of GaSb (0.7eV). Small InSb (
0.2 eV), V b 2 VI b s has a short crystallization time, can be easily made amorphous, and has a crystallization temperature higher than that of Te.
The following general formula, ([(GaSb)too-y(InSb)lIoo-,
Since it is composed of a composition represented by (M), 1 too-+(N)z, it is possible to improve its amorphization without causing a decrease in crystallization rate or crystallization temperature. In addition, when the amorphous phase corresponds to the recording state, recording sensitivity can be improved, and phase separation of the recording material becomes less likely to occur, making it possible to prevent segregation of the material.

Here, the above general formula, that is, [(GaSb)to. −, (M)x}100
−, (N), and [[(GaSb)too-y(InSb
) y] too-, (M), 1 too-+ (N), even when the composition ratio of Group VIb elements such as Te exceeds 10 at%, the method disclosed in JP-A-62-241145 The reason why the crystallization rate is less likely to decrease and the crystallization temperature is less likely to decrease compared to the above method is as follows.

In other words, "For crystallization rate 1, the above [(GaS
b), oo-, (M)xl+oo-, (N), is a stoichiometric compound of GaSb and a stoichiometric compound of V
G, which is a synthesis between b2VIb, or a stoichiometric compound
V b 2 VI b which is a stoichiometric compound with aSb
This is thought to be because the main part of s is obtained by synthesis between a mixture of two or more types of s, and the crystallization rate of both GaSb and Vb2VIb is fast.
b) too-y(InSb)y] too-, (M), 1
GaS where too-+(N)+ is a stoichiometric compound
b and InSb, and the stoichiometric compound V b 2
Synthesis between VI b r or G which is a stoichiometric compound
aSb and InSb, and the stoichiometric compound Vb2V
Ib, the main part thereof is obtained by synthesis between a mixture of two or more types of Ib, and the above-mentioned Garb and InSb both have a zinc blende type structure and have the same crystal structure, and the above-mentioned GaSb, Vb, VIb It is inferred that this is because the crystallization speeds of both are fast.

On the other hand, regarding the crystallization temperature j, the above [(GaSb)+ o o -x (ML] t
ooo −t (N)+, and [[(GaSb)t
oo-y(InSb)y]+oo--(M)-1too
As mentioned above, the crystallization temperature of Vb2VIbl that constitutes a part of -+(N)+ is higher than that of Te, and the above G
Since the crystal structures of aSb and InSb are the same, V b
It is inferred that this is because the effect on the crystallization temperature due to the addition of 2 VT b s and InSb is small.

In addition, a recording material represented by the following general formula, [[(GaSb
)1aa-y(InSb)y]too-t(M)xl
The reason why the recording sensitivity of too-+(N), that is, the amorphous sensitivity improves, is that the optical band gap of InSb, which partially replaces GaSb, is 0.2 eV, compared to the value of GaSb (0.7 eV). Because it is extremely small, due to partial substitution of this InSb, the above [[(caSbLoo-, Nn5b)y]too
We infer that this is because the absorption rate of the light beam at -, (M), 1 tco-+(N)+ is increased.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In this example, for the (GaSb)-(Sb, Tes)-(Sb) system recording material included in the invention according to claim 1, the composition area indicated by diagonal lines in the composition diagram 1 in FIG. It has been confirmed that these materials were effective;
On the other hand, the following materials included in the invention according to claim 2, namely (GaSb)-(InSb)-(Sb, Te+
)-(Sb) system recording material is shown in Figure 3.1 Composition diagram 1
It has been confirmed that the materials within the composition range indicated by the middle diagonal lines were effective.

Examples related to optical recording media to which each recording material is applied will be specifically described below.

◎First Example The following first to fourth examples apply the invention according to claim 1. That is, as shown in FIG. 1, the optical recording medium according to this example includes an acrylic substrate (1) with a thickness of 1.2 mm, and a thick film formed on this substrate (1) by RF magnetron sputtering. Sa1100
n SiL substrate protective layer (2), and this substrate protective layer (
2) [(GaSb)ss(Sb
2Tes)1s] aiSbti recording material layer (3), a 1100n thick 5i02 protective layer (4) formed on this recording material layer (3) by the same method, and this protective layer ( 4) Thickness 200n formed in the same way on top
m of A1 alloy heat diffusion layer (5), and this heat diffusion layer (5)
) is laminated on top of the acrylic protective plate (7) with a thickness of 1.2 mm, which is laminated via an adhesive layer (6) of ultraviolet curable resin.

Note that light absorption in this optical recording medium ranges from visible light to near-infrared light, and at least 400 to 860 nm.
It could be used as an optical recording medium within this range.

When using this optical recording medium, the amorphous phase of the recording material corresponds to the recorded state, while the crystalline phase of the recording material corresponds to the erased state, as in the past.

The recording method using this optical recording medium will be described below. First, the optical recording medium was rotated at a speed of 180 Orpm and uniformly irradiated with a 780 nm semiconductor laser to initialize the optical recording medium.

Next, the initialized optical recording medium is rotated at a speed of 180 Orpm, and in this state, a single recording/erasing beam whose output is selectively switched (output during recording = 20 mW, output during erasing: 12 mW) ) was irradiated to record and erase information by override.

On the other hand, the optical recording medium on which information has been written is rotated at a speed of 180 rpm, and in this state, a laser beam with an output of 1 mW is irradiated onto the recording material layer (3), and this reflected beam is read by a light receiving element. The recorded information was played back.

In the recording method using this optical recording medium, the recording/erasing time is 50 ns or less, which significantly improves the recording/erasing speed compared to the method using conventional optical recording media. A practical value of 25 dB or more was also obtained.

On the other hand, while heating the recording material layer (3), its reflectance is monitored, and the temperature at which the reflectance begins to change rapidly is defined as the "crystallization temperature 1", and the temperature at which the recording material layer (3) applied to this optical recording medium The crystallization temperature was determined to be 210°C or higher, indicating that the stability of the amorphous phase was also sufficient.

Furthermore, although an information rewriting test was conducted up to 105 times, segregation of the recording material did not occur and no major deterioration in recording characteristics was observed.

In addition, Sb is not added (GaSb) s s (Sb
When a similar rewriting test was carried out using an optical recording medium to which a recording material of 2Tes)+s was applied, deterioration of recording and erasing characteristics appeared after 10'' times, indicating that Sb was added [(caSb) IS(Sb2Tel)i]
It was confirmed that aiSb+s has improved resistance to repeated rewriting.

◎Second Example The optical recording medium according to this example has the above-mentioned recording material layer (3)
[(G
aSb)so(SbzTei)io]t+5b2i except that the optical recording medium according to the first embodiment is -.

Then, the optical recording medium initialized in the same manner as in the first embodiment is
It is rotated at a speed of 800 rpm, and in this state, a single recording/erasing beam whose output is selectively switched (15 mW output during recording, 6 mW output during erasing) is irradiated to record and erase information by override. While erasing, the written optical recording medium is rotated at a speed of 180 Orpm,
In this state, the recording material layer (3) was irradiated with a laser beam with an output of 1 mW, and the reflected beam was read by a light receiving element to reproduce the recorded information.

As a result, even in the recording method using the optical recording medium according to the second embodiment, the recording/erasing time is 50 ns or less, the recording/erasing speed is significantly improved, and the erasing characteristic is also 25 dB or more, which is practical. A value was obtained.

In addition, when the crystallization temperature of this recording material was determined, it was found to be 17
The stability of its amorphous phase is sufficient at temperatures above 0°C,
In addition, although an information rewriting test was performed up to 105 times, segregation of the recording material did not occur and no major deterioration in recording characteristics was observed.

In addition, Sb is not added (GaSb) so (Sb2T
When a similar rewriting test was conducted using an optical recording medium to which the es)io recording material was applied, the recording and erasing characteristics deteriorated after 10 times, and Sb was added [(GaSb)i o (Sb2'tel)to ]
It was confirmed that the repeated rewriting resistance of ts5b2i was improved.

◎Third Example The optical recording medium according to this example has the above-mentioned recording material layer (3).
[(G
aSb)+. (Sb2'rel)i o]ooSb
The difference between the optical recording medium and the optical recording medium according to the first embodiment is -, except that the optical recording medium is constituted by +o.

Then, the optical recording medium initialized in the same manner as in the first embodiment is
It is rotated at a speed of 800 rpm, and in this state, a single recording/erasing beam whose output is selectively switched (13 mW output during recording, 6 mW output during erasing) is irradiated to record and erase information by override. While erasing, the written optical recording medium is rotated at a speed of 1800 rpm,
In this state, the recording material layer (3) was irradiated with a laser beam with an output of 1+++W, and the reflected beam was read by a light receiving element to reproduce the recorded information.

As a result, even in the recording method using the optical recording medium according to the third embodiment, the recording/erasing time is 50 ns or less, the recording/erasing speed is significantly improved, and the erasing characteristic is also 25 dB or more, which is practical. A value was obtained.

In addition, when the crystallization temperature of this recording material was determined, it was found to be 15
The stability of its amorphous phase is sufficient at temperatures above 0°C,
In addition, although an information rewriting test was performed up to 106 times, segregation of the recording material did not occur and no major deterioration in recording characteristics was observed.

In addition, Sb is not added (GaSb) lo (Sb2
When a similar rewriting test was conducted using an optical recording medium to which the recording material of Tel) i + was applied, the deterioration of the recording and erasing characteristics appeared after 105 times. (SbzTes)o. ]eo
It was confirmed that Sblo had improved resistance to repeated rewriting.

◎Fourth Example The optical recording medium according to this example has the above-mentioned recording material layer (3).
[(G
aSb)s o (BjtTe+ )s + ] 7
This is the same as the optical recording medium according to the first embodiment except that it is configured with o Sbs o.

Then, the optical recording medium initialized in the same manner as in the first embodiment is
It is rotated at a speed of 80 Orpm, and in this state, a single recording/erasing beam whose output is selectively switched (output of 14 mW during recording, output of 8+r+W during erasing) is irradiated to record and erase information by override. While erasing
The written optical recording medium is rotated at a speed of 180 rpm, and in this state, a laser beam with an output of 1 mW is irradiated onto the recording material layer (3), and this reflected beam is read by a light receiving element to read the recorded information. Played.

As a result, even in the recording method using the optical recording medium according to the fourth embodiment, the recording/erasing time is 50 ns or less, the recording/erasing speed is significantly improved, and the erasing characteristic is also 25 dB or more, which is practical. A value was obtained.

In addition, when the crystallization temperature of this recording material was determined, it was found to be 16
The stability of its amorphous phase is sufficient at temperatures above 0°C,
In addition, although an information rewriting test was performed up to 106 times, segregation of the recording material did not occur and no major deterioration in recording characteristics was observed.

In addition, Sb is not added (GaSb)io(BizT
When a similar rewriting test was conducted using an optical recording medium to which ex)so recording material was applied, deterioration of recording and erasing characteristics appeared after 105 times, and Sb was added [(GaSb)so( Bi2Tei)so]+oSb+
It was confirmed that o's repeated rewriting resistance was improved.

◎Fifth Embodiment The following fifth to eighth embodiments apply the invention according to claim 2. That is, in the optical recording medium according to this example, the recording material layer (3) is made of ([(GaSb)so(I
nSb)to]+1(Sb2Te+)1i1 aiSb
The difference between the optical recording medium and the path according to the first embodiment is -, except that it is configured with +s.

Then, the optical recording medium initialized in the same manner as in the first embodiment is
It is rotated at a speed of 800 rpm, and in this state, a single recording/erasing beam whose output is selectively switched (17 mW output during recording, 9 mW output during erasing) is irradiated to record and erase information by override. While erasing, the written optical recording medium is rotated at a speed of 180 Orpm,
In this state, the recording material layer (3) was irradiated with a laser beam with an output of 1 mW, and the reflected beam was read by a light receiving element to reproduce the recorded information.

As a result, even in the recording method using the optical recording medium according to the fifth embodiment, the recording/erasing time is 50 ns or less, the recording/erasing speed is significantly improved, and the erasing characteristic is also 25 dB or more, which is practical. A value was obtained.

Further, as mentioned above, the output of the recording/erasing beam is 17 mW during recording and 9 mW during erasing, and in the case of the optical recording medium of the first embodiment in which part of GaSb is not replaced with InSb (in this case , 20mW when recording, 12mW when erasing
It was confirmed that the recording sensitivity was improved compared to the previous one (mW).

Furthermore, when the crystallization temperature of this recording material was determined, it was found to be 20
The stability of the amorphous phase was sufficient at temperatures above 0°C, and even though information rewriting tests were conducted up to 108 times, segregation of the recording material did not occur and no major deterioration in recording characteristics was observed.

In addition, [(GaSb) to (InSb) iol5s(Sb
When a similar rewriting test was conducted using an optical recording medium to which a recording material of zTes) (InSb)+o]1s(S
It was confirmed that the repeated rewriting resistance of b+Te+)+il asSbs+ was improved.

◎Sixth Example The optical recording medium according to this example has the above-mentioned recording material layer (3)
[[(
GaSb)so(InSb)iol1o(Sb2Tei
) between the optical recording medium and the optical recording medium according to the first embodiment except that it is composed of soltiSb2i.

Then, the optical recording medium initialized in the same manner as in the first embodiment is
It is rotated at a speed of 80 Orpm, and in this state, a single recording/erasing beam whose output is selectively switched (10 mW output during recording, 6 mW output during erasing) is irradiated to record and erase information by override. While erasing, the written optical recording medium is rotated at a speed of 180 rpm,
In this state, the recording material layer (3) was irradiated with a laser beam with an output of 1 mW, and the reflected beam was read by a light receiving element to reproduce the recorded information.

As a result, even in the recording method using the optical recording medium according to the sixth embodiment, the recording/erasing time is 50 ns or less, the recording/erasing speed is significantly improved, and the erasing characteristic is also 25 dB or more, making it practical. A value was obtained.

In addition, as mentioned above, the output of the recording and erasing beam is lomW during recording and 5 mW during erasing, and in the case of the optical recording medium of the second embodiment in which Garb is not partially replaced with nSb (in this case , 15mW when recording, 6mW when erasing
It was confirmed that the recording sensitivity was improved compared to W.

Furthermore, when the crystallization temperature of this recording material was determined, it was found to be 17
The stability of the amorphous phase was sufficient at temperatures above 5°C, and even though the information was rewritten up to 10 times, segregation of the recording material did not occur and no major deterioration of the recording properties was observed.

In addition, [(GaSb)a o (InSb)4o ] s
When a similar rewriting test was conducted using an optical recording medium to which a recording material of o (Sb2Te+)io was applied,
After 105 times, the deterioration of recording and erasing characteristics becomes apparent.
Sb is added [[(GaSb)ao(InSb
)+o]1o(Sb+Te+)iol tiSb2+ was confirmed to have improved resistance to repeated rewriting.

◎Seventh Example The optical recording medium according to this example has the above-mentioned recording material layer (3).
However, as in the first example, a film of 1001 m thick ([(GaSb)
so(InSb)iol1i(SbzTes)*sl
*This is the difference between the optical recording medium and the optical recording medium according to the first embodiment except that it is composed of oBi+o.

Then, the optical recording medium initialized in the same manner as in the first embodiment is
It is rotated at a speed of 800 rpm, and in this state, a single recording/erasing beam whose output is selectively switched (8 mW output during recording, 4 mW output during erasing) is irradiated to record and erase information by override. While erasing, the written optical recording medium is rotated at a speed of 1800 rpm, and in this state a laser beam with an output of 1 mW is applied to the recording material layer (
3), and the reflected beam was read by a light receiving element to reproduce the recorded information.

As a result, even in the recording method using the optical recording medium according to the seventh embodiment, the recording/erasing time is 50 ns or less, the recording/erasing speed is significantly improved, and the erasing characteristic is also 25 dB or more, which is practical. A value was obtained.

In addition, as mentioned above, the output of the recording and erasing beam is 8 mW during recording and 4 mW during erasing, and in the case of the optical recording medium of the third embodiment in which a part of GaSb is not replaced with InSb (in this case , 13mW when recording, 6mW when erasing
It was confirmed that the recording sensitivity was improved compared to the previous one.

Furthermore, when the crystallization temperature of this recording material was determined, it was found to be 15
The stability of its amorphous phase is sufficient at temperatures above 0°C,
In addition, although an information rewriting test was performed up to 10 times, segregation of the recording material did not occur, and no major deterioration in recording characteristics was observed.

In addition, [(GaSb)zo(InSb)iol+1(Sb
When a similar rewriting test was conducted using an optical recording medium to which a recording material of 2Tes) to(InSb)7ol+1(S
b2Tes)*il 5oBi+o was confirmed to have improved resistance to repeated rewriting.

◎Eighth Example The optical recording medium according to this example has the above-mentioned recording material layer (3)
[[(
GaSb)zo(InSb)iol5o(Bi2Tei
) sat +5Sb2i.

Then, the optical recording medium initialized in the same manner as in the first embodiment is
It is rotated at a speed of 80 Orpm, and in this state, a single recording/erasing beam whose output is selectively switched (14 mW for recording, 6 mW for erasing) is irradiated to record and erase information by override. While erasing, the written optical recording medium is rotated at a speed of 1800 rpm,
In this state, the recording material layer (3) was irradiated with a laser beam with an output of 1 mW, and the reflected beam was read by a light receiving element to reproduce the recorded information.

As a result, even in the recording method using the optical recording medium according to the eighth embodiment, the recording/erasing time is 50 ns or less, the recording/erasing speed is significantly improved, and the erasing characteristic is also 25 dB or more, making it practical. A value was obtained.

In addition, as mentioned above, the output of the recording and erasing beam is 13 mW during recording and 6 mW during erasing, and in the case of the optical recording medium of the fourth embodiment in which GaSb is not partially replaced with nSb (in this case , 14mW when recording, 8mW when erasing
It was confirmed that the recording sensitivity was improved compared to W.

Furthermore, when the crystallization temperature of this recording material was determined, it was found to be 17
The stability of its amorphous phase is sufficient at temperatures above 0°C,
In addition, although an information rewriting test was performed up to 10 times, segregation of the recording material did not occur, and no major deterioration in recording characteristics was observed.

In addition, [(GaSb)ao(InSb)to)so(Bi
When a similar rewriting test was conducted using an optical recording medium to which a recording material of 2Tes)so was applied, deterioration of recording and erasing characteristics appeared after 10' times, and Sb was added ([(GaSb) zo(InSb)iol1n(B
It was confirmed that i+Te+)iol+5Sb2i had improved resistance to repeated rewriting.

〔Effect of the invention〕

According to the invention according to claim 1, the recording material is GaSb, which has a short crystallization time and high stability of the amorphous phase although it is difficult to become amorphous, and GaSb which has a short crystallization time and is easy to become amorphous and has a crystallization temperature. The following general formula, [(GaSb)+oo-, (M)iloo-+(N), synthesized with Vb2VIb, which is higher than Te, and Sb or old, which has the effect of inhibiting the phase separation phenomenon of mixed materials. +
Since it is composed of a composition expressed by , it is possible to improve the amorphous state without causing a decrease in the crystallization rate or crystallization temperature, and it is difficult for the phase separation phenomenon of the recording material to occur. This makes it possible to prevent material segregation.

Therefore, information can be written or rewritten at high speed, this recorded information can be retained for a long period of time, and durability against repeated rewriting can be improved.

On the other hand, according to the invention according to claim 2, the recording material is made of GaSb, which has difficulty in becoming amorphous but has a short crystallization time and high stability of the amorphous phase, and has a crystal structure identical to that of GaSb (zincblende type). InSb (structure) with a smaller optical bandgap than GaSb (0.7eV)
(0.2eV), Vb2VIbI, which has a short crystallization time and is easy to become amorphous, and has a crystallization temperature higher than Te, and Sb or Bil, which has the effect of inhibiting phase separation of mixed materials. General formula, f[(GaSb)too-y(InSb)y]too-
Since it is composed of a composition represented by , and when the amorphous phase corresponds to the recording state, recording sensitivity can be improved, and phase separation of the recording material becomes less likely to occur, making it possible to prevent segregation of the material. .

Therefore, information can be written or rewritten at high speed, this recorded information can be retained for a long period of time, and the resistance to repeated rewriting can be improved. Since the output of the light beam can be reduced, the thermal stress applied to the optical recording medium is reduced, which has the effect of further improving the repeated rewriting durability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of an optical recording medium according to an example;
Figure 2 shows (GaSb)-(Sb, Te+)-(Sb
) composition diagram 1 and Figure 3 for recording materials based on
(GaSb)-(InSb)-(SbzTei)-(
4 and 5 are diagrams explaining the principle of recording and erasing in phase change method 1. [Explanation of symbols] (1)...Substrate ( 3)...Recording material layer 3, recording material layer

Claims (2)

[Claims] (1) A recording material layer that undergoes a reversible phase change by means of light, heat, etc. is provided on the substrate, and the change in optical properties accompanying this phase change is used to record/reproduce information, or to record/reproduce/reproduce information. In the optical recording medium to be erased, the recording material is [(GaSb)_1_0_0_-_x(M)_x]_1
_0_0_-_z(N)_z (However, M is V on the periodic table
It is composed of group b elements and group VIb elements, and its chemical formula is Vb_
2VIb_3 or a mixture of two or more of these stoichiometric compounds, while N is Sb or Bi
and the ranges of x and z are respectively 7 mol%≦x≦95 mol%, 5 mol%≦z≦40 mol%). . (2) A recording material layer that undergoes a reversible phase change by means of light, heat, etc. is provided on the substrate, and the change in optical properties accompanying this phase change is used to record/reproduce information, or to record/reproduce/reproduce information. In the optical recording medium to be erased, the recording material is {[(GaSb)_1_0_0_-_y(InSb)_
y]_1_0_0_-_x(M)_x}_1_0_0_
−_z(N)_z (However, M is the Vb group element on the periodic table.
It is composed of group VIb elements and its chemical formula is Vb_2VIb_3
A stoichiometric compound or a mixture of two or more of these stoichiometric compounds, where N is Sb or Bi, and the ranges of x, y, and z are each 5 mol%≦
x≦85 mol%, 2 mol%≦y≦70 mol%, 5 mol%≦z≦40 mol%.