RU2455739C2 - Line of laser diodes - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: line of laser diodes consists of parallel-connected laser diodes based on semiconductor A₃B₅ laser heterostructures, multilayer oxides and multilayer contact metal coating on the top and bottom planes of the line, wherein external conducting layers of the metal coating are made from germanium.

EFFECT: reduced mechanical stress arising in the line of laser diodes during manufacture.

2 cl, 5 dwg

Description

The invention relates to semiconductor electronics, in particular to the production of microwave powerful gallium arsenide discrete devices and integrated circuits, hybrid power modules, computer circuits and boards, and can also be used in optoelectronics for research, development and production of high-power semiconductor lasers, laser semiconductor arrays and laser systems based on them.

Powerful semiconductor lasers based on A ₃ B ₅ heterostructures and solid solutions based on them are most effective for operation in the wavelength range of 0.5-1.8 microns; the coefficient of conversion of electric energy into a directed light wave reaches 75% (1-3). Such lasers are used to pump fiber amplifiers and solid-state lasers, to record information, in the manufacture of printers, navigation systems, medical equipment and powerful technological processing devices. Especially promising is the use of laser matrices to create ultra-powerful space emitters using solar energy, since semiconductor lasers require low-voltage direct current generated by solar panels.

An experimental comparative analysis of semiconductor lasers from a number of leading companies and an analysis of patent literature showed that all firms use the classic version of a rigid combination of materials for laser production; The version is called classical, since the most common MOS system in M-semiconductor electronics is used (M - metal, O - oxide, P - semiconductor).

Representation of the laser structure in the form of a MOS system makes it possible to use chemical thermodynamics methods to assess the structural and phase instability of boundary states in a line of laser diodes, which is extremely important in the design and manufacture of reliable and durable semiconductor lasers and complex laser arrays (4).

The basis of the laser MOS system is a double semiconductor heterostructure A ₃ B ₅ . Among a large number of compounds A ₃ B ₅ and solid solutions based on them, formed by elements of the 3rd group (Al, Ga, In) and elements of the 5th group (N, P, As, Sb, Bi), the most common in production semiconductor lasers for various purposes is gallium arsenide. Gallium arsenide has the structure of a sphalerite crystal. The sphalerite structure can easily be represented as a combination of two cubic face-centered lattices inserted one into another, displaced relative to each other by a quarter of the diagonal and consisting of one kind of atoms each. Elements of the fourth group (Si, Ge, C) have such a combination of lattices, but formed by atoms of the same type (diamond lattice).

The main physical properties of compounds A ₃ B ₅ (gallium arsenide, indium phosphide) and some elements of the 4th group are presented in the table.

Physical properties of gallium arsenide, indium phosphide and germanium Gaas Ge Inp Au one 2 3 four 5 Lattice constant, A ° 5.65 5.65 The distance between the two nearest atoms, A ° 2.45 2.45 Coefficient of thermal expansion, 1 / deg 5.39 × 10 ⁶ 6.1 × 10 ⁶ 5.39 × 10 ⁶ 14.2 × 10 ⁶ The density in the solid state, g cm ³ 5,316 5,328 19.3 Resistivity, ohm cm 3.7 × 10 ⁸ 47 Thermal conductivity at 300 ° K, cal cm s hail 0.11 0.14 0.16 0.7

It can be seen that the lattice constant and the coefficient of thermal expansion of gallium arsenide and germanium are similar with a significant difference in their physical and technological characteristics.

The idea of the invention is to create a stable semiconductor-semiconductor system, (1) using the same properties of the elements in the line, and improve the technological characteristics of the line, (2) using differences in the properties of the combined elements of the MOS system.

Figure 1 shows the line of laser diodes - LDB (5). Dimensions LDB: length - 10 mm, thickness - from 50 to 150 microns, width - 0.8-3.0 mm. LDB can contain 19, 25, 50, 75 and more laser diodes (single laser diode emitter - SLDE).

The SLDE structure is shown in FIG. The basis of the structure is the layers of dilute solid solutions based on gallium arsenide. After creating a semiconductor heterostructure, the complex process of the formation of multilayer metallization begins.

On the upper and lower planes of the semiconductor (П) base, multilayer contact metallization (M) is created parallel to the heterostructure layers: first, thin layers of metals are sprayed to obtain ohmic (non-rectifying) contacts. Then a three-layer metal barrier is created, for example (Ti-Mo-Ni), between the ohmic contacts and the outer conductive layers of gold. The external metallization layers, as shown by the analysis of LDB and SLDE of all firms producing a line of laser diodes, consist of (Au) gold with a thickness of more than 350 nm, Fig.3.

On two parallel end faces of the crystal perpendicular to the semiconductor layers and the direction of the light wave are deposited oxide layers (O) - front and rear mirrors. This is how a laser semiconductor MOS structure is produced.

The prototype of the invention is a line of laser diodes, figure 4. which was used for the development, manufacture and research of high-power semiconductor lasers with an “XYZ” microchannel cooling system (6). Laser radiation power of more than 60 W in a continuous mode of radiation at a temperature of 25 degrees. Wavelength l = 808 nm; differential efficiency - 60%. However, with good electrical characteristics of the laser, its optical properties are unacceptable: the curvature of the line before being mounted on the heat exchanger, as well as the curvature of the laser radiation line exceeds 1 μm. This is the result of creating a tense and, therefore, unstable MOS system, due to the rigid combination of gold and other metals with a thickness of more than 800 (KTP of gold - 14.2 × 10 ⁶ deg ^-1 ) with a double semiconductor A ₃ V ₅ heterostructure (KTP - 5 , 39 × 10 ⁶ deg ^-1 , more than 2.5 times) and end multilayer oxides (oxides of Al, Si, Zr).

The aim of the invention is the creation of a stable thermodynamic laser MOS system to improve the physical and technological characteristics of a line of laser diodes.

The goal is achieved by the fact that:

1. A line of laser diodes, consisting of parallel-connected laser diodes based on semiconductor A ₃ B ₅ laser heterostructures having coatings made of multilayer oxides (rear and front mirrors) at the outer ends, as well as multilayer contact metallization on the upper and lower planes of the line, characterized in that the conductive contact metallization layers are made of semiconductor elements of similar type and crystal lattice parameters and thermal expansion coefficient with the semiconductor ₃ a ₅ l grain heterostructure and solid solutions based on A ₃ B _5, 5.

2. The line of laser diodes according to claim 1, characterized in that the external conductive layers of contact metallization are made of (intermediate between (31) - Ga and (33) - As elements of the Mendeleev DI system) element (32) germanium with the addition of elements forming the required conductivity and ohmic contact.

3. The line of laser diodes according to claim 1, characterized in that the ratio of the thicknesses between the external conductive layers of contact metallization on the upper and lower planes of the line corresponds to zero curvature of the line (Smile = 0) and the minimum voltage in semiconductor A ₃ B ₅ laser heterostructures.

The invention is applicable to all types of semiconductor lasers and laser arrays. Thus, single-chip lasers can be manufactured, that is, lasers consisting of a single laser diode, multi-chip lasers — laser diode arrays and laser arrays, which can consist of dozens of laser diode arrays. In this case, the conductive semiconductor layer can be performed both on one side (+) and on both sides of the A ₃ B ₅ heterostructure (+ and -).

The invention is simple technical implementation. The invention contributes to the improvement of the technology for the production of semiconductor lasers, since obtaining low-voltage laser lines with zero smile in multilayer MOS systems (metal - oxide - semiconductor) is a complex technological task.

The figures given in the description depict the following.

Figure 1. The line of laser diodes (LDB).

Figure 2. Single-diode laser double heterostructure scheme (SLDE).

Figure 3. Laser metallization system A ₃ V ₅ heterostructure in LDB.

Figure 4. Laser MOS system (Metal - Oxide - Semiconductor) - prototype.

Figure 5 Laser POP system (Semiconductor - Oxide - Semiconductor) - invention.

Literature

1. Zh.I. Alferov and others. High power CW operation of InGaAsN lasers at 1.3 µm. Electron Lett., 1999, vol. 35, No.19, pp. 2-5.

2. Zh.I. Alferov and others. InAs / InGaAs / GaAs quantum dot lasers of 1.3 µm range with high (88%) differential efficiency. IEEE Journal of Quantum Electronics, 2002, Vol. 38, No.19, 1104-1106.

3. A.B. Lyutetskiy et al. High-power diode lasers (l = 1.7-1.8 μm) based on asymmetric quantum confined InGaAsP / InP quantum heterostructures of separate separation. FTP, 2009, v. 43, issue 12, p. 1666-1649.

4. V.A. Filonenko. The adhesion mechanism in metal - dielectric systems. J. Phys. Chemistry. 1976, 3, 726-729.

5. M. Jansen and others. High performance laser diode bars with aluminum-free active regions. Optics express, 1999, Vol.4, No.1.

6. V. Apollonov, S. Derzhavin, V. Filonenko and others. Higly efficient heat exchanges for laser diode arrays. Proceedings of SPIE, Vol. 3889, 2000, 71-81.

Claims (2)

1. The line of laser diodes, consisting of parallel-connected semiconductor laser diodes based on semiconductor A3B5 laser heterostructures, multilayer oxides - mirrors, and multilayer contact metallization on the upper and lower planes of the laser diode line, characterized in that the outer conductive metallization layers on the upper and the lower planes of the line of laser diodes are made of germanium. 2. The line of laser diodes according to claim 1, characterized in that the ratio of the thicknesses between the outer conductive metallization layers on the upper and lower planes of the line corresponds to zero curvature of the line (Smile = 0) and the minimum voltage in the lines of laser diodes.

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