JP2950927B2 - Semiconductor laser - Google Patents

Description

The present invention relates to an InGaAlP-based semiconductor laser that emits visible light.

(B) Conventional technology The device structure of the conventional semiconductor laser shown in FIG.
neseJournalof Applied Physics Vol.28, No.9, Septembe
r, 1989, pp. 1615-1621. In the figure, the AuZn / Au electrode 101, the p-type GaAs cap layer 10
2, n-type GaAs block layer 103, p-type In _0.5 (Ga _1-X Al _X ) _0.5
P cladding layer 104, non-doped In _0.5 Ga _0.5 P active layer 10
5, n-type In _0.5 (Ga _1-x Al _x ) _0.5 P cladding layer 106, n-type Ga
An As buffer layer 107, an n-type GaAs substrate 108, and an AuGe / Au electrode 109.

As in this example, the non-doped InGaP active layer 105 is
In the device structure sandwiched between the InGaAlP cladding layers 104 and 106, the dopants of the p-type and n-type cladding layers 104 and 106 (eg, silicon Si, selenium Se, and zinc Zn) are mixed into the active layer 105 during the manufacturing process, and the reliability of the device is reduced. There was a problem that it reduced.

FIG. 6 shows the Se and Zn concentration profiles of the device having the structure of FIG. 5 using Se as the dopant in the n-type cladding layer 106, and FIG. 7 shows the Si and Zn of the device also using Si as the dopant. 3 shows a Zn concentration profile. However, the dopant concentration was measured using SIMS.

From these figures, when Se is used as the n-type dopant,
It can be seen that a large amount of Se is taken into the active layer 105 due to the memory effect of Se.

On the other hand, when Si is used as the dopant, the amount of Si taken into the active layer 105 is reduced as compared with the case of Se, but the amount of Si taken in at the interface between the active layer 105 and the n-type cladding layer 106 increases.

6 and 7, it can be seen that Zn as a p-type dopant is also largely diffused and taken into the active layer 105.

(C) Problems to be Solved by the Invention In view of the above-mentioned problems of the prior art, the present invention has a p
It is an object of the present invention to provide a new device structure for reducing a phenomenon in which a type or n-type dopant is incorporated.

(D) Means for Solving the Problems The present invention has a p-type and n-type cladding layer made of an InGaAlP-based compound semiconductor, and a non-doped active layer. Between the active layer and the p-type cladding layer, the semiconductor laser provided with a non-doping cladding layer between the active layer and the p-type cladding layer. And an average thickness of the non-doped cladding layer provided between the active layer and the n-type cladding layer is 300 ° or less.

And, as a p-type dopant of the p-type clad,
Use Zn.

(E) Action The amount of p-type and n-type dopants taken into the active layer is controlled by the non-doped cladding layers on both sides of the active layer,
Moreover, the forward voltage is stabilized.

(F) Embodiment The semiconductor laser of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a cross-sectional view showing an element structure.
Cr-Au electrode 1, p-type GaAs cap layer 2, n-type GaAs block layer 3, p-type In (Ga _0.5 Al _0.5) P cladding layer 4, an In (Ga
_0.5 Al _0.5 ) P non-doped clad layer 5, non-doped In
GaP active layer _{6, In (Ga 0.5 Al 0.5} ) P undoped cladding layer 7, n-type In (Ga _0.5 Al _0.5) P cladding layer 8, n-type InGa
A P buffer layer 9, an n-type GaAs substrate 10, and a Cr-Sn-Au electrode 11.

The respective layers are sequentially epitaxially grown on one main surface of the substrate 10 using a well-known MOCVD method, and the thicknesses of the non-doped cladding layers 5 and 7 are respectively 100 °.

FIG. 2 is a diagram showing a doping profile when Si is used as an n-type dopant and Zn is used as a p-type dopant in a semiconductor laser device having the device structure of FIG. Compared to FIG. 7, the active layer 6
It can be seen that the incorporation of the dopant into the inside is reduced.

That is, in the conventional device, the active layer 105 and the p-type clad layer 1
At the interface between the active layer 105 and the n-type cladding layer 106, about 3 × 10 ¹⁷ (cm ⁻³ ) of Zn is diffused.
While Zn diffusion of about ¹⁷ (cm ⁻³ ) is observed, in the device of the present invention, 1 × 10 ¹⁷ and 2.5 × 10 ¹⁷ (2.5 × 10 ¹⁷ ) are formed at the interface between each of the non-doped cladding layers 5 and 7 and the active layer 6. cm- ³ ) Zn
You can only see the spread of

FIG. 3 shows the average thickness of the non-doped cladding layers 5 and 7 and 2
It is a diagram showing a relationship between the forward voltage V _F at 00MA. Here, the average film thickness is determined by the following equation.

Until the average film thickness is about 300Å to see this figure it is clear that the change of the V _F is less stable.

FIG. 4 is a current characteristic diagram showing the results of a life test of a conventional device and the device of the present invention. Here, the stripe width of the element, the thickness dimension of the active layer 6, and the resonator length are each 5 μm.
0.08μm, 300μm, no end face coating, life test 5
The measurement was performed at 0 ° C., 5 mW, by the APC (Automatic Power Control) method.

As is clear from this figure, the conventional device does not show a large change in current up to about 1500 hours, but the current value greatly changes after 1500 hours, compared to the device of the present invention. It was observed that the initial current value was retained even after reaching 4000 hours.

(G) Effects of the Invention As described above, the present invention controls the diffusion of the dopant into the active layer by interposing the non-doped cladding layers on both sides of the active layer, stabilizes the forward voltage, This has the effect of extending the life and improving the yield.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a structure of a semiconductor laser device of the present invention, FIG.
Figure 3 is a diagram similarly showing the relationship between the film thickness and V _F of the non-doped layer, Figure 4 compared the lifetime of the device and a conventional device of the present invention FIG, Fig. 5 structure cross-section of a conventional element FIG. 6 is a diagram showing a doping profile of a conventional device using Se as an n-type dopant, and FIG. 7 is a diagram showing a doping profile of a conventional device corresponding to FIG. 4 ... p-type cladding layer, 6 ... non-doped active layer, 5, 7 ... non-doped cladding layer, 8 ... n-type cladding layer.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Ryoharu Hiroyama 2-18-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (56) References JP-A-4-49691 (JP, A) JP-A Sho 63-140590 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01S 3/18

Claims (2)

(57) [Claims] 1. A semiconductor device comprising: a p-type and n-type cladding layer comprising an InGaAlP-based compound semiconductor; and a non-doped active layer, wherein a non-doped active layer is provided between the active layer and the p-type and n-type clad layers. In a semiconductor laser provided with a cladding layer, Si is used as an n-type dopant of the n-type cladding layer, and a non-doped cladding layer is provided between the active layer and the p-type cladding layer; A semiconductor laser characterized in that the average film thickness with a non-doped cladding layer provided between the layers is 300 mm or less. 2. The semiconductor laser according to claim 1, wherein Zn is used as a p-type dopant of said p-type cladding.