JPS6019676B2 - semiconductor light emitting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor light emitting device, and in particular, an object of the present invention is to obtain a highly efficient semiconductor light emitting device by improving the structure of a green light emitting element made of GAP material.

Since Gap has a wide forbidden band width, it can be doped with zinc and oxygen as a luminescent center to obtain red luminescence, and doped with nitrogen to produce green color. Recently, there has been a large demand for green light emitting elements, and there has been a strong demand for high performance green light emitting elements. There are the following methods for manufacturing a green light emitting device using a secondary gap as a material.

That is, a method of doping nitrogen on a Gap substrate by vapor phase growth to form an n-type growth layer and creating a pn junction by zinc diffusion, and a method of forming a p-layer and an n-type growth layer by doping with nitrogen using a Gap substrate by liquid phase growth.
There are a method of forming a pn junction by growing the pn junction separately from a layer, and a method of forming a pn junction on a gap substrate in a single process. In any case, in order to increase the luminous efficiency of a semiconductor light emitting device, the injection rate of minority carriers into the light emitting region should be increased, the lifetime of the minority carriers should be made as long as possible, and as many nitrogen atoms as the luminescent center should be injected into the crystal as possible. It is necessary to introduce However, green light-emitting elements formed by conventional methods do not have luminous efficiency that meets the above-mentioned requirements, and are still unsatisfactory in terms of reproducibility and mass production. The present invention has been made in consideration of these points, and provides a semiconductor light-emitting device using a green light-emitting element that has high performance and can be mass-produced with good reproducibility.

That is, in both cases, an n-layer is first grown on an n-type Gap substrate by a liquid phase growth method, a first p-layer doped with nitrogen, which is a luminescent center, is grown on top of the n-layer, and a second p-layer is further grown on top of that. A green light emitting element is obtained by growing the green light emitting element, and is characterized in that the first p layer is used as a light emitting region. In such a device, the impurity profile is No, where the donor concentration of the n-layer is No, and the acceptor concentrations of the first and second p-layers are N^, , N^2, respectively.
/N^,>1, N^2/N^,>1. Preferably N. /N^, it is better to set it to >10.
Therefore, carrier injection occurs from the n layer to the first p layer, and the first p layer becomes a light emitting region. Since the luminous efficiency depends on the injection efficiency if the luminescent center concentration is constant, it is preferable that the ratio ND/N^ be large. Furthermore, the donor of the n-layer used in the above process is silicon, and the acceptors of the first p-layer and the second p-layer are carbon and zinc, respectively. Embodiments of the present invention will be described below with reference to the drawings.

As shown in Fig. 1, a recess 2 is formed in the boat body 1, and a solution reservoir 3 is sent onto the boat main body 1 to slide over the recess 2 from left to right in the figure. A growth device is formed. This is inserted into a reaction tube (not shown) during operation. When manufacturing a green light emitting device, a quartz plate 4 is placed in the recess 2, and an n-type cap substrate 5 is placed on top of the quartz plate 4.

The main body of the solution reservoir 3 is made of carbon, and the inside is lined with quartz 6, and a Ga solution 7 is placed therein. This device is placed in a reaction tube, and hydrogen is flowed as an atmospheric gas at a rate of 50 som/hr. When a predetermined temperature, for example 1000°C, is reached, the port liquid reservoir is slid onto the substrate by operating from outside the reactor. For example, add solution 8 to a thickness of 2
The solution is applied uniformly to the legs, and the solution reservoir 3 is slid on the boat body 1 so that it does not cover the substrate as shown in FIG. This state is maintained for 30 minutes to partially dissolve the substrate. Next, the substrate is gradually cooled to 970° C., and the n-layer is grown on the substrate, with silicon liberated by the reaction of quartz with hydrogen serving as the main donor. Since silicon is the donor, the broach is very flat. When the growth of the n-layer was completed, the atmospheric gas was changed to argon.
At the same time, NH3 gas is flowed at a rate of 0.5 evening/min to dope nitrogen.

The concentration of this NH3 gas is 0.5% and diluted with argon. After this state is maintained for 6 hours, it is gradually cooled again and nitrogen is doped to grow the first p layer. At this time, the main acceptor is carbon. In other words, donor Si
reacts with a portion of NH3 to form nitrides, so the donor concentration decreases due to the introduction of N, and carbon, which had been a residual acceptor, becomes an acceptor, forming a p-layer. When the temperature reaches 930 qo, the temperature decrease is stopped again and 6
The solution is held for a while, and zinc vapor is sent to make the solution highly concentrated p-type, and cooling is started again to grow a second p-layer.

The main acceptor at this time is zinc. 900qo
When the temperature reaches 100, only the argon is supplied and everything else is turned off, cooled to room temperature, and the substrate is taken out.

A part of the substrate on which the n-layer, first and second p-layers were grown in this manner was cleaved, the cleavage plane was etched by a known method, and the thickness of the grown layer was measured.

As shown in Figure 3, the n layer is 25# and the first p layer is 20#.
, the second p layer had 30 peaks, and the impurity concentration was measured by the Schottky method after polishing at an angle of about 5" and the results were as shown in Figure 3. The vertical axis represents the impurity concentration, and the horizontal axis represents the thickness of each layer.
Furthermore, after forming a p-type electrode and an n-type electrode on this substrate, it was made into a pellet with an elevation angle of 0.3 and the luminous efficiency was measured. The average of the 20 pellets was 0.25% (lf = 2 A). , 0.05 to 0.05 for those made by various conventional methods.
1%, it showed a much higher luminous efficiency, and the variation was small, within ±20%.

In this way, the characteristics were significantly improved. Regarding mass production, when the boat was made larger and the board was re-coated, the luminous efficiency was as high as 0.22 to 0.35%, and the variation was within ±30%. It has been found that it is possible to mass-produce devices with significantly improved characteristics compared to light-emitting devices. the n-layer and the first and second
The donors and acceptors used in the growth of the p-layer are silicon, carbon, and zinc; however, according to the gist of the present invention, other elements, such as tellurium and selenium, may be used as donors if they can be controlled as described above. Of course. Furthermore, although the above is an example in which the luminescent center is added only to the first p-layer, the donor level decreases due to the reaction between Si and N&, and just before the first p-layer is formed, some n
Although it is conceivable that nitrogen may be introduced into the layer, even in such a structure, the main light emitting region is the first p-layer, which naturally does not contradict the spirit of the present invention. In this way, the product of this invention eliminates the defects of the conventional product, and
The present invention is a semiconductor light emitting device with good characteristics that uses a green light emitting element that has high luminous efficiency, good reproducibility, and can be mass produced, and is industrially useful.

[Brief Description of the Drawings] Figures 1 and 2 are cross-sectional views showing the state when the temperature is rising and when the temperature is falling when forming a green light-emitting element using the Gap substrate of the present invention. FIG. 3 is a curve diagram showing the impurity concentration of each layer of the light emitting device of the invention. 1...Boat body, 2...Concave part of boat body, 3...Solution reservoir, 5...Gap
Substrate, 6...Quartz tube for solution reservoir, 7...
Solution, 8... Solution on the substrate. Book 1 Figure 2 Collection 84

Claims (1)

[Claims] 1. An n-layer grown without adding a luminescent center on an n-type GaP substrate and having a uniform donor concentration distribution in the thickness direction; a first p-layer grown and having a uniform acceptor concentration distribution in the thickness direction and doped with a luminescent center; and a first p-layer grown on the first p-layer and having a uniform acceptor concentration distribution in the thickness direction. and a second p layer, and when the donor concentration of the n layer is N_D, the acceptor concentration of the first p layer is N_A_1, and the acceptor concentration of the second p layer is N_A_2, N_D/N_A_1>1
, N_A_2/N_A_1>1. 2. The semiconductor light emitting device according to claim 1, wherein the donor of the n-layer is silicon.