DESCRIPTION OPTICAL INFORMATION RECORDING MEDIUM AND ITS RECORDING AND/OR READING METHOD Technical Field [0001] The present invention relates to an optical information recording medium and its recording and/or reading method. The present invention is preferably adapted especially to a write-once optical information recording medium. Background Art [0002] In optical information recording media including a CD and a DVD, an organic dye material has mainly been used as a write-once optical information recording medium material so far. The reason is that when the organic dye material is used, it is relatively easy to sustain interchangeability with a read-only memory (ROM), for which a relatively high reflectance is requested under the standards, over a wavelength band of laser light that is used for recording or reading. Moreover, the recording medium can be produced through a simple process of forming a reflective layer according to a sputtering method after spin-coating the organic dye. The use of the organic dye material is advantageous in terms of a cost of manufacture such as plant investment. [0003] However, since the wavelength of laser light to be employed in recording or reading has gotten shorter and laser light in a wavelength band of blue violet (wavelength of about 400 run) has come to be used, circumstances become different. Specifically, it is not easy to prepare an organic dye, which can cope with the laser light of the wavelength, in terms of recording sensitivity and a signal property. The layer construction of a recording medium cannot be readily accomplished through the conventional simple process. Further, the fact that when the recording medium is manufactured according to the spin coat method, the homogeneity of a land part with a groove part cannot be retained has been found apparently disadvantageous in terms of a push-pull signal or crosstalk in high-density recording. [0004] In order to meet the requirements, the employment of an inorganic recording material instead of the organic dye material is currently encouraged in earnest. The practical use of a recording medium employing the inorganic recording material has been shelved because the recording medium is hardly interchangeable with the ROM of a high reflectance and an expensive sputtering apparatus is needed to form many layers of the material, though the recording medium has been studied in the past. However, the dependency of the inorganic recording material on the wavelength of employed laser light is generally not as high as that of the organic material is. Moreover, formation of many recording layers that has often been performed in recent years (inclusion of many recording layers makes the recording capacity of an optical disk of the same size two or more times larger) can be more readily achieved than employment of the organic dye material. Therefore, the use of the inorganic recording material as a new-generation optical recording material in place of the organic dye material has become a mainstream, and the inorganic recording material has been put to practical use. [0005] As the inorganic recording material, various types of materials have been proposed in the past. For example, an optical recording medium employing a recording layer that has two or more layers of thin films made of different metallic materials joined has been proposed (refer to a patent document 1) . In the optical recording medium, a multilayer film is partly recomposed into an alloy to form a single film using heat dissipated with irradiation of laser light in order to form record marks . As applied examples of this method, various forms have been proposed with the material varied differently (refer to, for example, a patent document 2). Moreover, a write-once optical recording medium using an oxide compound for the recording layer has been proposed (refer to, for example, patent documents 3 and 4). [0006] However, the foregoing recording media cannot be said to fully satisfy all conditions required for the write-once optical information recording medium. Specifically, required are that information recorded in the write-once optical information recording medium is preserved stably over a long period as it initially is (archival property) , that a signal is not impaired by reading laser light during signal reading (reading stability) , and that the writing property is sustained without degeneration caused by normal long-term preservation (shelf-life property). The aforesaid conventional recording media cannot be said to satisfactorily have these properties. Moreover, from the viewpoints of a cost of manufacture of a recording medium or reserve of a margin in a manufacturing process, the number of layers constituting a recording medium is requested to be as small as possible, and the manufacturing process is requested to be simple. Moreover, sufficient sensitivity and a sufficient response speed are desired in terms of recording and reading properties. Thus, an excellent recording/reading signal is guaranteed for a wide range of linear velocities. [0007] Proposed as an optical recording medium employing an inorganic recording material are: a medium having a reco2:ding layer made of an alloy containing Zn, Sn, Sb, and Te (refer to a patent document 5) ; a medium having a recording layer made of a recording material that contains as a principal component a compound expressed as AxB1-x (where A denotes at least one element selected from a group of Zn, Ga, In, Si, Ge, Sn, Bi, and Sb, B denotes at least one element selected from a group of Se, Te, S, and 0, and x denotes a compositional ratio determined with a range (2.0 to 3.0) of values of a mean coordination number) (refer to a patent document 6) ; a medium having a recording layer formed with an alloy thin film expressed as Mw( (SbzTe1-z) 1-w (0≤w<0.3, 0.50, b>0, c>0, d>0, e>0, f>0, h>0, and a+b+c+d+e+f+h=100 are met (refer to a patent document 10) ; a medium including a recording layer that has a composition expressed as SbaXbSncZndSieOfSh where X denotes an element selected from among In, Ge, Al, Zn, Mn, Cd, Ga, Ti, Si, Te, Nb, Fe, Co, W, Mo, S, Ni, 0, Se, Tl, As, P, Au, Pd, Pt, Hf, and V, and a>0, b>0, c>0, d>0, e>0, f>0, h>0, and a+b+c+d+e+f+h=100 are met (refer to a patent document 11) ; and a medium including a recording layer that contains at least one metal M selected from a group of Ni, Cu, Si, Ti, Ge, Zr, Nb, Mo, In, Sn, W, Pb, Bi, Zn, and La, and an element X which binds with the metal M when being irradiated a recording laser beam so as to produce a crystal of a compound with the metal M (refer to patent documents 12 and 13) . [0008] (Table Removed) Patent document 11: JP-A-2003-182237 Patent document 12: JP-A-2005-125726 Patent document 13: JP-A-2005-129192 Disclosure of the Invention Problems to be Solved by the Invention [0009] As mentioned above, there has been difficulty in inexpensively providing a write-once optical information recording medium in which: recorded information is stably preserved for a long period as it initially is; a signal is not impaired by reading laser light during signal reading; the writing property is retained without degeneration caused by normal long-term preservation; satisfactory sensitivity and a satisfactory response speed are offered; and excellent recording and reading properties can be realized with respect to a wide range of linear velocities or recording powers. A problem to be solved by the present invention is to provide an optical information recording medium that satisfies all the above conditions, and its recording and/or reading method. Means for Solving the Problem [0010] The present inventor et al. have made studies in efforts to solve the above problem. Consequently, the present inventor et al. have found and experimentally verified that the foregoing conditions can be satisfied by adopting a material, which contains ZnS, SiO2, and Sb as principal components, as a material of a recording layer of an optical information recording medium, and come to devise the present invention. In order to solve the problem, the first invention provides an optical information recording medium characterized in which it includes a recording layer which contains ZnS, SiO2, and Sb as principal components. [0011] The second invention provides a recording and/or reading method for an optical information recording medium including a recording layer which contains ZnS, Si02, and Sb as principal components. The recording and/or reading method is characterized in that recording and/or reading is performed by causing laser light, of which wavelength is equal to or larger than 385 nm and equal to or smaller than 415 nm, to fall on the recording layer. [0012] In the optical information recording medium, information is recorded by causing the recording layer to undergo a qualitative change, which is accompanied by a change in an optical constant, through irradiation of laser light. The recording layer may contain, if necessary, in addition to ZnS, SiO2, and Sb, at least one element selected from a group of Ga, Te, V, Si, Zn, Ta, and Tb. The recording layer preferably has a composition that satisfies a formula (1) below. [(ZnS)x(Si02)i-x]y(SbzXi-2)1-y ... (I) where 02 of the recording layer 13 from reacting on each other. A protective layer having the capability of a barrier against an Ag atom or the like of, for example, an SiN film is employed. In the second embodiment, the construction other than the above point is identical to that of the first embodiment. According to the second embodiment, the same advantage as that of the first embodiment can be provided. [0037] Next, an optical information recording medium in accordance with the third embodiment of the present invention will be described below. Fig. 13 shows the optical information recording medium 3. As shown in Fig. 13, in the optical information recording medium 3, the order in which a reflective layer 11, a protective layer 12, a recording layer 13, and a protective layer 14 are layered is reverse to that in the optical information recording medium 1 in accordance with the first embodiment. Specifically, in the optical information recording medium 3, the protective layer 14, recording layer 13, protective layer 12, and reflective layer 11 are sequentially layered on a substrate 10, and a light transmissive protective layer 15 is layered on the uppermost layer of the reflective layer 11. Recording/reading is performed on the optical information recording medium 3 by causing laser light to enter or leave the substrate 10 side. In this case, as the material of the substrate 10, a material that hardly exhibits absorbency with respect to recording/reading laser light, for example, a plastic material such as polycarbonate or an acrylic resin is adopted. In the third embodiment, the construction other than the above point is identical to that of the first embodiment. According to the third embodiment, the same advantage as that of the first embodiment can be provided. [0038] Next, an optical information recording medium in accordance with the fourth embodiment of the present invention will be described below. Fig. 14 shows the optical information recording medium 4. As shown in Fig. 14, in the optical information recording medium 4 , similarly to the optical information recording medium 1 in accordance with the first embodiment, a reflective layer 11, a protective layer 12, a recording layer 13, and a protective layer 14 are sequentially layered on a substrate 10. However, it is different from the optical information recording medium 1 in accordaace with the first embodiment that an intermediate layer 17 and a recording layer 18 are sequentially layered on the protective layer 14, and that a light transmissive protective layer 15 is layered on the recording layer 18. The optical information recording medium 4 is a two-layer optical information recording medium including two layers of recording layers 13 and 18. Recording/reading is performed on the optical information recording medium 4 by causing laser light to enter or leave the light transmissive protective layer 15 side. [0039] The intermediate layer 17 can be formed by, for example, applying an ultraviolet curable resin, which does not exhibit absorbency in the wavelength band of laser light used for recording/reading after being cured, by a desired thickness (for example, 20 to 30 µm) using a spin coater or the like, or by bonding a light curable PSA, which does not exhibit absorbency in the wavelength band of laser light used for recording/reading after being cured, and then performing ultraviolet irradiation. A substrate having concavo-convex groove tracks may be used to transfer the concavo-convex groove tracks during ultraviolet irradiation. The second recording layer 18 is constructed to exhibit a sufficiently high transmittance that permits recording/reading laser light to enter or leave the first recording layer 13 through the second recording layer so as to perform recording or reading. The recording layer 18 may be a recording layer of a write-once type or a rewritable type or may be a recording layer permitting reading alone. [0040] (Example 2) The optical information recording medium 4 on which recording/reading is performed by an optical disk recording/reading apparatus employing two groups of objective lenses that have a numerical aperture of 0.85 and a semiconductor laser light source that emits light at a wavelength of 405 nm within the wavelength band of blue violet was fabricated as mentioned below. As the substrate 10, a polycarbonate substrate having grooves, which had a thickness of 1.1 mm, a track pitch of 0. 32 |j.m, and a groove depth of 20 nm, on one side thereof was fabricated using an injection mold. On the polycarbonate substrate, an Ag alloy film of 100 nm thick serving as the reflective layer 11, a Ta20s film of 30 nm thick serving as the protective layer 12, the recording layer 13 of 20 nm thick, and a Ta205 film of 30 nm thick serving as the protective layer 14 were sequentially formed according to the sputtering method. After an adhesive of an ultraviolet curable type was applied to the Ta2C>5 film of the uppermost layer by a thickness of 25 fo,m according to the spin coat method, a polycarbonate stamper was used to transfer groove tracks, and ultraviolet irradiation was performed in order to form the intermediate layer 17. The second recording layer 18 was formed on the intermediate layer 17. Further, after an adhesive of an ultraviolet curable type was applied to the recording layer 18 by a thickness of 15 p.m according to the spin coat method, a polycarbonate light transmissive sheet (film) of 85 (j.m thick is placed, and ultraviolet irradiation was performed in order to form the light transmissive protective layer 15. Thus, the optical information recording medium 4 was fabricated. [0041] The thus fabricated optical information recording medium 4 was measured. For measurement, an ODU-1000 (laser light wavelength: 405 run) manufactured by Pulstec Industrial Co., Ltd. , a spectrum analyzer R32 67 manufactured by Advantest Corp. , and a j itter analyzer LE1876 manufactured by Leader Electronics Corp. were employed. Signal measurement was performed on the optical information recording medium 4 under a linear velocity of 4.92 m/s and a channel bit length of 74.50 nm which were conformable to the standard for the Blu-ray Disc DL50GB density. Signal recording was performed at, in addition to the linear velocity of 4.92 m/s, a double linear velocity of 9.84 m/s and a quadruple linear velocity of 19.68 m/s. For jitter measurement, a signal having been treated by a limit equalizer manufactured by Pulstec Industrial Co., Ltd. was used. The equalizer gain was 7.0 dB. [0042] Recording/reading measurement was performed on the optical information recording medium 4. Under a reflectance of 4.6 % and a linear velocity of 4.92 m/s (velocity that is one time higher) , when a recording power was 9.1 mW, a jitter was 6.3 %. When modulation was defined as (I8H-I8L)/I8H in relation to a signal level of I8H for each 8T space part and a signal level of I8L for each 8T mark part, the value was 57 %. Thus, the optical information recording medium 4 exhibited quite excellent recording and reading properties. Under a double linear velocity of 9.84 m/s (velocity that is twice higher), when the recording power was 6.8 mW, the j itter was 6.5% and the modulation was 58 % . Under a quadruple linear velocity of 19.68 m/s (velocity that is four times higher), when the recording power was 11.9 mW, the jitter was 6.5 % and the modulation was 65 %. [0043] Fig. 15 and Fig. 16 show the results of recording/reading measurement. As seen from Fig. 15, the optical information recording medium 4 has high recording sensitivity with respect to any of linear velocities and exhibits quite excellent recording and reading properties. As seen from Fig. 16, assuming a jitter of 8.5 % is the upper limit, a margin for a variation in a recording power is wide enough to tolerate a power variation of about + 15 % under any linear velocity. Thus, the optical information recording medium 4 has a sufficiently wide power margin. According to the fourth embodiment, a two-layer write-once optical information recording medium having the same advantage as that of the first embodiment can be inexpensively provided. [0044] Next, an optical information recording medium in accordance with the fifth embodiment of the present invention will be described below. Fig. 17 shows the optical information recording medium 5. As shown in Fig. 17, in the optical information recording medium 5, similarly to the optical information recording medium 1 of the first embodiment, a reflective layer 11, a protective layer 12, a recording layer 13, and a protective layer 14 are sequentially layered on a substrate 10. A difference from the optical information recording medium 1 in accordance with the first embodiment lies in a point that: an intermediate layer 19, a recording layer 20, an intermediate layer 21, a recording layer 22, an intermediate layer 23, and a recording layer 24 are further sequentially layered on the protective layer 14; and a light transmissive protective layer 15 is layered on the recording layer 24. The optical information recording medium 4 is a four-layer optical information recording medium having four layers of recording layers 13, 20, 22, and 24. Recording/reading is performed on the optical information recording medium 4 by causing laser light to enter or leave the light transmissive protective layer 15 side. [0045] The intermediate layers 19, 21, and 23 can be formed by applying an ultraviolet curable resin, which does not exhibit absorbency within the wavelength band of laser light used for recording/reading after being cured, by a desired thickness (for example, ranging from 20 to 30 µm) using a spin coater or the like, or bonding a light curable PSA which does not exhibit absorbency within the wavelength band of laser light used for recording/reading after being cured, and then performing ultraviolet irradiation. A substrate having concavo-convex groove tracks may be used to transfer the concavo-convex groove tracks during ultraviolet irradiation. The second recording layer 20, third recording layer 22, and fourth recording layer 24 are constructed to exhibit a transmittance that is high enough to permit recording/reading laser light to enter or leave the first recording layer 13 through the recording layers so as to enable recording and reading. The recording layers 20, 22, and 24 may be recording layers of a write-once type or a rewritable type or may be recording layers permitting reading alone. According to the fifth embodiment, a four-layer write-once optical information recording medium having the same advantage as that of the first embodiment can be inexpensively provided. [0046] The embodiments of the present invention have been concretely described so far. However, the present invention is not limited to the embodiments. Various variants can be produced based on the technological idea of the present invention. For example, the numerical values, materials, structures, and shapes employed in the first to fifth embodiments and examples 1 and 2 are mere examples. If necessary, different numerical values, materials, structures, and shapes may be adopted. WE CLAIMS 1. (amended) An optical information recording medium characterized in that: the optical information recording medium includes a recording layer which contains ZnS, SiO2, and Sb as principal components; the recording layer contains as least one element selected from a group of Ga, Te, V, Si, Zn, Ta, and Tb; and the recording layer has a composition which satisfies the following formula (1): [(ZnS)x(Si02)i.x]y(SbzX1.z)i.y ... (I) where 0