JPH0196979A - mask semiconductor laser - Google Patents

Abstract

PURPOSE:To easily form a fine hole in a mask layer and to eliminate the ageing expansion of the hole by forming a mask material for shielding the radiated light of a semiconductor laser of an alloy of a metal element having high reflectivity within the wavelength of the radiated light and an element having large optical energy absorption. CONSTITUTION:A mask layer 14 is formed on the light irradiating region of a semiconductor laser 12, and a pinhole 16 is formed at a position corresponding to the light irradiating region of the layer 14. For example, in 3-element series semiconductor laser of GaAlAs, an alloy containing 50:50wt. of Au and Ge is formed as the material of the mask layer, and deposited 2000Angstrom thick by vacuum depositing by a resistance heating method on an irradiated cleaved surface. When an injecting current is, for example, set to 112mA while an LD is being fired, an irradiating hole is formed at the mask layer. When the injecting current is fixed to 60mA and the LD is continuously fired, no variation in the hole occurs, thereby providing excellent durability.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a mask semiconductor laser, and more specifically, the present invention relates to a mask semiconductor laser, and more specifically, it is used as a light source for optical memory, magneto-optical memory, etc., and it is easy to form fine holes that determine the spot diameter of the laser beam. The present invention relates to a mask semiconductor laser in which the mask is made of a durable material that does not spread over time.

[Prior art]

Generally, in semiconductor lasers used as light sources for optical memory, magneto-optical memory, etc., in order to increase the recording density, it is necessary to reduce the spot diameter of the laser beam.Normally, the laser beam is passed through an extremely small pinhole. It has been experimentally found that the beam diameter of light passing through a pinhole is approximately equal to the pinhole diameter in the so-called near field, which is very close to the pinhole. A mask semiconductor laser has been proposed as a light source for such a small diameter laser beam.

However, conventionally proposed masked semiconductor lasers have a problem in that micropores formed in the mask layer enlarge over time due to laser light. This is because the material of the mask layer greatly affects the formation of micropores and its durability against laser light. For example, if the material is relatively easy to absorb semiconductor laser light and easily forms micropores, its durability against light may be affected On the other hand, metals that absorb light easily, that is, have a high reflectance, are considered to have good durability, but they have the problem that it is difficult to form microscopic pores with the power of a semiconductor laser. It is something that you have.

〔the purpose〕

The present invention uses an alloy material to realize a light source for high-density recording and reproduction of optical memories, magneto-optical memories, etc., and has a mask layer that is easy to form micropores and has durability that prevents these micropores from expanding over time. The object of the present invention is to provide a mask semiconductor laser having the following characteristics.

〔composition〕

The mask semiconductor laser of the present invention is characterized in that the mask material that blocks semiconductor laser radiation is formed of an alloy of a metal element that has a high reflectance within the wavelength of the semiconductor laser's emitted light and an element that has a large optical energy absorption. That is.

That is, the present invention combines the characteristics of the two materials by using an alloy of a metal element with high reflectance and an element with high optical energy absorption as a material in the mask layer of a mask semiconductor laser.

FIG. 1 shows an embodiment of a mask semiconductor laser according to the present invention. The mask semiconductor laser 10 has a mask layer 14 provided on the surface of the light emitting region of the semiconductor laser 2, and a pinhole 6 is provided in a portion of the mask layer 14 corresponding to the light emitting region.

Examples of the semiconductor laser 12 include GaAQAs ternary semiconductor lasers, typified by semiconductor lasers with wavelengths of 780 nm and R30 nm, which are currently commercially available, but it goes without saying that other suitable semiconductor lasers can also be used. The mask layer 14 is required not only to not transmit the laser radiation light, but also to be thermally melted and evaporated by the semiconductor laser radiation light in order to form emission micropores. Furthermore, it is necessary that the minute holes, that is, the pinholes 16, undergo very little change over time due to laser radiation. As materials that satisfy these characteristics, Au and A are metal elements that have a high reflectance in the wavelength range of semiconductor laser radiation.
ge AΩ.

Semiconductor elements that have large absorption of light energy in the same wavelength range include Ga and Si.

or Zn, Cd, Ti, etc.

In the present invention, elements having these characteristics are alloyed to form a mask material.

More specifically, Au-Ge, Au-8i, Ag-G
e.

Ag-8i, A Q-8i, A Q-Ge, Cu
-Ge, Cu-8L, Au-Te, Au-8e, Ag
-Te, Ag-8e and the like. Appropriate alloy materials are used depending on the emission wavelength range of the semiconductor laser.

Moreover, by changing the alloy composition, it can be applied to a wide range of semiconductor lasers.

Specific Example 1 A masked semiconductor laser having the configuration shown in FIG. 1 was produced according to the following procedure. First, as a semiconductor laser, G
aAl2As double hetero type was used (maximum rated output;
5mW + continuous operation output: 3mW, oscillation wavelength: 780n
m).

As for the mask layer material, the weight ratio of Au and Ge is so
: An alloy of SO was prepared and deposited on the exit cleavage surface by vacuum evaporation using a resistance heating method to a film thickness of 2000 mm. The vapor deposition conditions at that time were as follows.

Vapor deposition conditions Vapor deposition source material: A u-G e alloy 50: 50 (overlapping percentage) Vapor deposition source temperature: 1200°C Vapor deposition source boat: Tungsten Vacuum degree: IXl0-5 torr Substrate (semiconductor laser) temperature: 20 to 40°C In the mask semiconductor prepared as above.

When the current was monitored while the LD was turned on, when the injection current was set to 112 mA, the monitored current suddenly changed, so it was determined that an injection hole was formed in the mask layer, and the atV was measured using an electron microscope at a magnification of 15,000 times. As a result, 1.
It was confirmed that a circular injection hole with a diameter of 2 μm was formed. Next, the injection current was fixed at 60 mA and continuous lighting was performed to test the variation in the shape of the injection hole. As a comparative example, Ge
A mask semiconductor laser with an injection hole of 1.3 μm and a diameter of 1.3 μm was used as a mask layer. Table 1 shows their changes over time.

As is clear from Table 1, the mask semiconductor laser using the Au-50G e alloy as the mask layer shows no change in the emission hole due to continuous lighting, indicating that it has extremely good durability.

Specific Example 2 Next, as a mask layer material, the weight ratio of Au and Ge is 30:
An alloy of No. 70 was prepared and deposited to a thickness of 2000 nm on the emission hexagonal surface of a semiconductor laser by vacuum deposition using the resistance heating method in the same manner as in Example 1. The vapor deposition conditions at this time are shown below.

Vapor deposition conditions Vapor deposition source material: Au-Ge alloy 30: 70 (weight percent) Vapor deposition source temperature: 1200°C Vapor deposition source boat: Tungsten Vacuum degree: I Xl0-storr substrate (semiconductor laser) temperature: 20 to 40°C or higher When we checked the monitor current while turning on the mask semiconductor laser we had created, we found that when the injection current was 86 mA, the monitor current suddenly changed, so we determined that an injection hole had been formed in the mask layer and examined it using an electron microscope. When observed at a magnification of 15,000 times, it was confirmed that a circular injection hole with a diameter of 1.3 μm was formed.

Next, continuous lighting was performed with the injection current fixed at 60 mA, and changes in the shape of the injection hole over time were tested.

The results are shown in Table 2 below. In addition, as a comparative example, a mask semiconductor laser with an injection hole of 1.3 μm and a diameter of 1.3 μm and a mask layer made of Ge was used.

Table 2 From Table 2, when the weight ratio of the Au-Ge alloy is 30:70, changes over time are observed compared to the case of 50:50 in Example 1, but the durability is greater than that of Ge alone. You can see that it has been improved.

Specific Example 3 Next, as a mask layer material, the weight ratio of Au and Ge is 70:
An alloy of No. 30 was prepared and deposited to a film thickness of 2000 nm on the emission hexagonal surface of a semiconductor laser by vacuum deposition using the resistance heating method in the same manner as in Example 1.2. The vapor deposition conditions at this time are shown below.

Vapor deposition conditions Vapor deposition source material: Au-Ge alloy 70: 30 (weight percent) Vapor deposition source temperature: 1200°C Vapor deposition source boat: Tungsten Vacuum degree: IXIF'torr Substrate (semiconductor laser) temperature: Conditions of 20 to 40°C or higher When we checked the monitor current while turning on the mask semiconductor laser we had prepared, we found that the monitor current changed rapidly when the injection current was 133 mA, so we determined that an injection hole had been formed in the mask layer and examined it using an electron microscope at a magnification of 15,000 times. Upon observation, it was confirmed that a circular injection hole with a diameter of 0.9 μm was formed.

Next, in order to check the durability of the mask semiconductor laser thus obtained, the injection current was fixed at 60 mA and continuous lighting was performed to test for changes in the shape of the injection hole over time. The results are shown in Table 3. In addition, as a comparative example, Ge
A mask semiconductor laser with an injection hole of 1.3 μm and a diameter of 1.3 μm was used.

As is clear from Table 3, the heavy weight ratio is 70:30.
The mask semiconductor laser using the Au-Ge alloy as a mask layer has a submicron-order aperture diameter of less than 1 μm, and is continuously lit.

The injection hole did not change over time, confirming that it had extremely good durability.

In addition, other alloys, such as Au-8L, Ag-Ge
, Ag-8i, A Q-8i, A Q-Ge,
Cu-Ge.

Cu-8i, Au-Te, Au-3e, Ag-T
Even when mask layers were formed by changing the composition of Ge, Ag-8e, etc., the changes in micropores over time were extremely small compared to the mask layer consisting only of Ge, as in each of the above specific examples. .

〔effect〕

According to the present invention as described above, a durable mask semiconductor laser is provided in which fine holes are formed in the mask layer even when the power of semiconductor laser light is applied, and the fine holes do not expand over time. ) has the effect of being

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram schematically showing the structure of an embodiment of a mask semiconductor laser according to the present invention.

Claims (1)

[Claims] 1. The mask semiconductor laser is characterized in that the mask material that blocks the semiconductor laser radiation is formed of an alloy of a metal element that has a high reflectance within the wavelength of the semiconductor laser's emitted light and an element that has a large optical energy absorption. mask semiconductor laser.