JPH01155678A - Semiconductor light emitting device - Google Patents

Abstract

PURPOSE:To obtain light rays sufficient in intensity without degrading an active layer in crystalline quality by a method wherein a layer or layers separate from each other which are several Angstrom - several hundred Angstrom in thickness and doped with light emitting impurity 10<19>/cm<3> or more in doses are formed in an active layer section. CONSTITUTION:A semiconductor laser is composed of a p-electrode 1, a p-InP cap layer 2, a p-InGaAsP layer 3, a blocking layers 4 and 5, an n-InGaAsP layer 6, an n-substrate 7, and an n-electrode 8. An active layer is composed of such a structure that layer which are 20Angstrom thick and doped with erbium 10<20>/cm<3> and InGaAsP layers (150Angstrom ) coincided with the substrate 7 in lattice constant are alternately laminated. By these processes, the light emitting impurity contained in the active layer is made to be 10<19>/cm<3> or more in average concentration and a light emitting output power grows to be 10mW or more. And, a device of this design can be oscillated in a single frequency independently of an external environment.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a semiconductor light emitting device.

2. Description of the Related Art Semiconductor lasers and light emitting diodes emit light by utilizing the unique electronic state of conventional semiconductors. Some light emitting devices of this type use other principles.

This is light emission using the level of 41 electrons derived from rare earth element ions added to the active layer.

shows the structure of this laser.

FIG. 3 shows a conventional laser structure. It is a type of oxide film stripe type laser. P-type InP (2) is used to improve electrical contact with the P-type electrode (1), and the current that flows into the active layer (6) is narrowed by the oxide film.
). The cladding layer ((4) 1(6)) confines light due to the difference in refractive index, and the oxide layer (3) narrows the light emitting area, lowering the threshold current as a whole. There is. These structures are fabricated on an n+InP substrate using the LPE method or the like.

The n-type electrode (8), which is the other electrode of the diode, is still attached to the back surface of the substrate (7). The active layer 5 is I n
It is GaAs P and is doped with erbium (Er) as a light-emitting impurity. Erbium becomes an ion at the position of the group ■ element, forms an ion level, and contributes to light emission. A feature of a laser using this principle is that single wavelength oscillation is easy. Furthermore, the emission wavelength does not depend on temperature, manufacturing conditions, etc., and is a value unique to the ion. By changing the ion species, the emission wavelength can be changed.

Until now, lasers using this principle have been grown by liquid phase epitaxial growth (LPE).

Luminescent impurities are added by mixing them into the active layer material melt.

Problems to be Solved by the Invention Currently realized lasers using light-emitting impurities do not have sufficient luminous intensity for practical use. In order to increase the light intensity, it is sufficient to increase the density of luminescent impurities. However, it is impossible to add high concentrations using the LPE method, which is the conventional crystal growth method. Another problem is that when impurities are added at a high density, the lattice constant changes, causing lattice mismatch between the active layer and other parts. When lattice mismatch exists, dislocations run in the crystal that grows on top of it. As a result, good quality crystals are not produced and the lifespan is deteriorated.

In view of the above-mentioned prior art, the present invention solves the problem of deterioration of crystal quality due to lattice mismatch.

Means for Solving the Problems The present invention provides an active layer with a light-emitting impurity of 10"9/l.
This is a semiconductor light emitting device in which a single layer or a plurality of layers with a thickness of several Å to several 100 doped with yA or more are formed at a distance.

Function: In a light-emitting device whose active layer is a strained superlattice structure having a layer containing the above-mentioned rare earth metal having 4 electrons as a light-emitting impurity ion, sufficient light intensity can be achieved without deteriorating the crystal quality of the active layer. It is possible to easily form an element structure that provides the following.

Examples Usually, molecular beam epitaxial growth method (
MBE method) can easily form an ultra-thin film structure. It is known that even in crystals with different lattice constants that contain light-emitting impurities, dislocations will not occur if the crystals are made thinner. Furthermore, thin crystal films having different lattice constants are alternately sandwiched between crystals having the same lattice constant as the substrate crystal. FIG. 1 shows four structural diagrams of a semiconductor laser according to an embodiment of the present invention. 1 is P-electrode, 2 is P-In
3 is a P cap layer, 3 is a P-InGaAsP layer, 4 and 6 are pulley layers, 6 is an n-InGaAsP layer, 7 is an n-substrate, and 8 is an n-electrode. FIG. 2 shows the semiconductor shown in FIG.

- is an enlarged view of the active layer region, that is, the part surrounded by a circle.

The active layer is InGaA with a lattice constant matching that of the substrate and a 20 layer doped with a light emitting impurity (erbium) at 1020/-.
It has a structure in which sP layers (160 people) are stacked alternately. As a result, the average concentration of luminescent impurities in the active layer is 1
o19/ctA or higher. A laser manufactured in this manner can have a light emission output of 10 mW or more. Moreover, because it uses light-emitting impurities, it oscillates at a single wavelength regardless of the external environment, and there is no wavelength fluctuation.

Effects of the Invention A semiconductor laser using the present invention is capable of single-wavelength oscillation during harmonic modulation, which is necessary as a light source for high-speed, large-capacity communication, and has the feature that there is no wavelength fluctuation due to temperature.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram of a semiconductor laser according to an embodiment of the present invention, FIG. 2 is an enlarged view of the active layer portion, and FIG. 3 is a structural diagram of a conventional laser. 1...P-electrode, 2...P-InP
13...P-InGaAsP, 4------
・n-InP, -5-・-P -I n P, 6-
...n-I nGaAs P, completed...n, -
M plate, 8...n- is the pole. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 (r

Claims (2)

[Claims] (1) The active layer should be provided with one layer or two or more layers spaced apart from each other with a thickness of several Å to several hundred Å to which 10^1^9/cm^3 or more of atoms with quantum electrons are added as light-emitting impurities. Characteristic semiconductor light emitting device. (2) The semiconductor light emitting device according to claim 1, characterized in that erbium is used as a light emitting impurity.