CN102832537B - Surface emission semiconductor laser device with two-inner-cavity contact type n-side light emergency framework supporting structure - Google Patents

Abstract

The invention discloses a surface emission semiconductor laser device with a two-inner-cavity contact type n-side light emergency framework supporting structure and a manufacturing method for the surface emission semiconductor laser device, and belongs to the technical field of semiconductor laser device manufacturing. According to the prior art, a p-type electrode and an n-type electrode are of the inner cavity contact type, but the electrodes are only introduced on the p side, so that the two-side DBR resistance is reduced. The main problem in the prior art is that the p-type electrode and the n-type electrode are formed on the same side and cannot be prepared to be closed, and the p-type electrode and the n-type electrode are semicircular, so that current distribution is asymmetric, and a light field formed by injecting current carrier induced photons is not uniform in distribution. According to the laser device structure, the p-type electrode and the n-type electrode are arranged on two sides of the device, so that the two-inner-cavity contact type structure is formed, and the injected current passes through a p-type DBR and an n-type DBR and directly enters an active region; and furthermore, the framework supporting structure and the manufacturing method of the framework supporting structure are adopted on the n side, so that the problem of collapse of the active region, which is caused by insufficient connection strength of the device structure, in a process for etching an n-type electrode window is solved.

Description

A double-cavity contact type n-side light emitting frame support structure surface emitting semiconductor laser

technical field

The invention belongs to the technical field of semiconductor laser manufacturing, and relates to a double-cavity contact type n-side light-emitting frame support structure surface-emitting semiconductor laser and a manufacturing method thereof.

Background technique

The output power of traditional surface-emitting semiconductor lasers is lower than that of edge-emitting lasers. This is because the traditional structure of surface-emitting semiconductor lasers is mainly composed of p-type DBR, active layer, and n-type DBR. The current passes through the p-type electrode and passes through the p-type DBR, The active region, n-type DBR, n-type substrate, and n-type electrode form a loop. This structure introduces a large equivalent resistance, and the impedance is mainly formed by the DBR, resulting in severe heating of the device, increased threshold current, and low internal quantum efficiency. reduce. Therefore, reducing the equivalent resistance of the device is one of the effective ways to obtain high-power and high-efficiency surface-emitting semiconductor lasers. In order to change this situation, it has been reported in the literature that the inner cavity contact electrode is only made on the p side, bypassing the p-type DBR resistor, and reducing the resistance of the device to a certain extent; it is also reported that the p-type and n-type electrodes are both on the p Side introduction to reduce the resistance of DBR on both sides, but the problem is that the p-type and n-type electrodes are on one side, and the electrodes cannot be prepared as a closed ring. Since it is a semi-ring type, according to the distribution of the current flowing through the resistance In principle, the distribution of current forms an asymmetry, and the distribution of the light field formed by injecting carriers to induce photons is not uniform. What needs to be pointed out here is that people have realized that double-cavity electrodes can reduce resistance, but their implementation and reports only propose one-sided introduction. There is a problem that must be solved. When the side-opening annular groove is introduced, since the remaining annular connection is only the thickness of the active area, which is about tens of nanometers, during the preparation process, including polishing, ultrasonic cleaning, etc., it is very easy to cause stress on the active area, Vibration avalanches.

Contents of the invention

The invention proposes a double-cavity contact type n-side light emitting frame support structure surface emitting semiconductor laser. This surface-emitting semiconductor laser changes the device structure, and its electrodes are introduced from both sides, so that the injection current bypasses the p-type DBR and n-type DBR and directly enters the active region, the current injection distribution is balanced, and the carrier-induced light field distribution is symmetrical. Uniform, the equivalent resistance of the entire device is effectively reduced, and the thermal characteristics of the device are also improved. At the same time, the frame supporting structure and its manufacturing method solve the problem of the collapse of the active area caused by insufficient connection strength of the device structure.

The present invention is achieved in this way, as shown in Fig. 1 for a schematic cross-sectional structure and Fig. 2 for a side view. The invention provides a double-cavity contact type n-side light emitting frame support structure surface emitting semiconductor laser. The structure of the laser includes: p-type electrode (1), p-type DBR (2), p-type ohmic contact layer (3), oxidation confinement layer (4), p-type confinement layer (5), active region (6 ), n-type confinement layer (7), n-type ohmic contact layer (8), n-type DBR (9), buffer layer (10), substrate (11), AR coating (12), n-type electrode (13 ), etching area (14), frame support structure (15).

It is characterized in that: the p-type electrode (1) and the n-type electrode (13) are both inner cavity contact electrodes, and the injection current bypasses the p-type DBR and n-type DBR and directly enters the active region;

It is characterized in that only the p-type ohmic contact layer (3) at the contact point between the p-type electrode (1) and the p-type ohmic contact layer (3) is partially re-doped, and the p-type ohmic contact layer (3) within the range of the vertical resonant cavity ) is not heavily doped, so as to ensure that the lasing photons are not largely absorbed by the heavily doped p-type ohmic contact layer (3);

It is characterized in that only the n-type ohmic contact layer (8) at the contact point between the n-type electrode (13) and the n-type ohmic contact layer (8) is partially re-doped, and the n-type ohmic contact layer (8) within the range of the vertical resonant cavity ) is not heavily doped, so as to ensure that the lased photons are not largely absorbed by the heavily doped n-type ohmic contact layer (8);

It is characterized in that: the p-type ohmic contact layer (3) contains a phase compensation layer, and its optical thickness satisfies the resonant wavelength of the laser.

It is characterized in that: the n-type ohmic contact layer (8) contains a phase compensation layer, and its optical thickness satisfies the resonant wavelength of the laser.

It is characterized in that: during the etching process of forming the n-type electrode window, the frame support structure (15) as shown in Figure 2 is used for masking, only the n-type DBR at (14) is etched away, and the resonance The connection stability between the device structure and the whole within the cavity range is enhanced.

It is characterized in that: the frame support channel of the frame support structure (15) can be four channels, or the other number of channels, and its width and shape are not limited, and this case only provides a schematic scheme demonstration.

The manufacturing process steps of the intracavity contact surface emitting laser proposed by the present invention are as follows:

1) Photolithography on the surface of p-type DBR (2);

2) Use photoresist as a mask to etch the p-type DBR (2) to the p-type ohmic contact layer (3);

3) Redoping the p-type ohmic contact layer (3) without photoresist protection;

4) Evaporate p-side ohmic contact electrode Ti/Pt/Au;

5) Stripping;

6) Overlay etching, etch to the surface layer of the p-type confinement layer (5);

7) Put the epitaxial wafer into the wet nitrogen oxidation device for oxidation, control the oxidation time, and make the oxidation confinement layer form an oxidation aperture with a suitable size to achieve good photoelectric confinement. At this time, the p-side fabrication is completed;

8) The substrate is thinned and polished, and a layer of anti-reflection film ZrO2 is evaporated;

9) Overlay engraving on the n side;

10) First use HF acid to remove the anti-reflection film ZrO that is not protected by photoresist on the n side, and then perform wet etching until the surface layer of the n-type ohmic contact layer (8) is etched to form an n-type electrode window;

11) Re-doping the n-type ohmic contact layer (8) at the window of the protective electrode without photoresist;

12) After completely removing the glue, use a negative glue overlay;

13) AuGe/Ni/Au electrodes are evaporated on the n side;

14) Stripping.

So far, the process has completed the double-cavity contact electrode of the n-side emitting surface-emitting semiconductor laser and its frame support structure. The injection current bypasses the p-type DBR and n-type DBR and directly enters the active region, and the equivalent resistance is greatly reduced. Thus, the device It has better thermal characteristics and overcomes the shortcomings of conventional structural technologies.

Instructions attached

Figure 1: Schematic diagram of the cross-sectional structure of a double-cavity contact n-side light-emitting frame support structure surface-emitting semiconductor laser: where: p-type electrode (1), p-type DBR (2), p-type ohmic contact layer (3), oxidation limiting layer (4), p-type confinement layer (5), active region (6), n-type confinement layer (7), n-type ohmic contact layer (8), n-type DBR (9), buffer layer (10), liner Bottom (11), AR coating (12) and n-type electrode (13)

Figure 2: The n-side pattern of the double-cavity contact type n-side light-emitting frame support structure surface emitting semiconductor laser, in which: the etching area (14), the frame support structure (15)

specific implementation plan

1. Using the metal organic chemical vapor deposition method, the n-type GaAs buffer layer is epitaxially grown sequentially on the n-type GaAs substrate with a thickness of about 635 μm; 28 pairs of n-type DBRs composed of Al _0.9 Ga _0.1 As/Al _0.1 Ga _0.9 As ; n-type GaAs ohmic contact layer; n-type confinement layer; 3 pairs of In _0.17 Ga _0.83 As/GaAs _0.92 P _0.08 strain compensation quantum well gain region, where In _0.17 Ga _0.83 As is the well material with a thickness of 6nm, GaAs _0.92 P _0.08 is the barrier material with a thickness of 4nm; p-type confinement layer; an oxidation confinement layer with a thickness of 30nm composed of Al _0.92 Ga _0.08 As; p-type GaAs ohmic contact layer; 30 pairs of Al _0.9 Ga _0.1 As/Al _0.1 Ga Gradient p-type DBR composed of _0.9 As.

2. Perform photolithography on the p side of the epitaxial wafer, and form the desired photolithography pattern after exposure and development.

3. The photolithography pattern is used as a mask, and wet etching or dry etching is performed to etch the p-type DBR (2) without photoresist protection to the surface layer of the ohmic contact layer (3).

4. Redoping the circular etched surface of the ohmic contact layer (3).

5. Use a magnetron sputtering apparatus to vapor-deposit the p-side ohmic contact electrode Ti (30nm)/Pt (50nm)/Au (200nm), and then peel off the surface.

6. Overlay etching, and then etch the p-type DBR (2) without mask protection until the surface layer of the p-type confinement layer (5).

7. Put the epitaxial wafer into a wet nitrogen oxidation device for oxidation. The oxidation temperature is 400°C, the temperature of the constant temperature water bath is 95°C, and the flow rate of _N2 is 1L/min. The oxidation time is controlled to form the oxidation aperture to achieve good photoelectric confinement.

8. On the n side of the epitaxial wafer, the substrate is thinned and polished mechanically, and a layer of anti-reflection film ZrO ₂ is evaporated to increase the light transmittance.

9. Double-sided alignment photolithography is used on the n side.

10. First use HF acid solution to etch away the anti-reflection film ZrO ₂ without photoresist as mask protection on the n side; use dry etching technology until the surface layer of the n-type ohmic contact layer is etched to form an n-type electrode window.

11. After the glue is completely removed, use negative glue to engrave.

12. Re-doping the n-type ohmic contact layer (8) at the window of the protective electrode without photoresist.

13. Evaporate AuGe/Ni/Au electrodes on the n side.

14. Stripping.

Claims (1)

1. A double-cavity contact type n-surface light emitting frame support structure surface-emitting semiconductor laser, characterized in that the laser comprises: a p-type electrode (1), a p-type DBR (2), a p-type ohmic contact layer (3 ), oxidation confinement layer (4), p-type confinement layer (5), active region (6), n-type confinement layer (7), n-type ohmic contact layer (8), n-type DBR (9), buffer layer (10), substrate (11), AR coating (12), n-type electrode (13), etching area (14), frame support structure (15); p-type electrode (1) and n-type electrode (13 ) are all inner cavity contact electrodes, and the electrodes are introduced from both sides, the injected current bypasses the p-type DBR and n-type DBR and directly enters the active area, and the equivalent resistance is greatly reduced; only for the p-side electrode (1) and the p-type ohmic The p-type ohmic contact layer (3) at the contact point of the contact layer (3) is locally re-doped, and the p-type ohmic contact layer (3) within the range of the vertical resonant cavity is not heavily doped, so as to ensure that the emitted photons are not re-doped The doped p-type ohmic contact layer (3) absorbs a lot; only the n-type ohmic contact layer (8) at the contact point between the n-type electrode (13) and the n-type ohmic contact layer (8) is partially re-doped, and the vertical resonance The n-type ohmic contact layer (8) within the cavity is not heavily doped, so as to ensure that the lasing photons are not absorbed by the heavily doped n-type ohmic contact layer (8); During the etching process, the frame support structure (15) is used for masking, only the n-type DBR at the etching area (14) is etched away, and the connection stability between the device structure and the whole within the resonant cavity is strengthened; During the etching process for forming the n-type electrode window, the frame support channel of the frame support structure (15) is four channels, and its width and shape are not limited.