JPH0322066B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a solid state light emitting device that emits a plurality of colors including blue.

A method for manufacturing a solid-state light emitting device has already been proposed in which red and green light emitting layers are laminated by liquid phase epitaxial growth. If you follow this manufacturing method,
In order to emit blue light as well, a blue light emitting layer must be further laminated using the liquid phase epitaxial growth method, but the temperature required to grow the blue light emitting layer is usually as high as around 1000°C. Therefore, the already formed red and green light emitting layers are easily damaged during the growth of the blue light emitting layer.

The present invention has been made in view of these points, and its feature lies in that a light-emitting layer contributing to blue light emission is formed by molecular beam epitaxial growth.

FIG. 1 shows an embodiment of the present invention. First, in the process shown in FIG. 1A, a first N-type layer 2, a first N-type layer 2, and a
Each GaP of the 1P type layer 3, the second P type layer 4 and the second N type layer 5
A light emitting substrate 6 is formed by sequentially stacking crystals.
At this time, Zn (zinc) and O (oxygen) are added near the first PN junction 7 at the boundary between the first N-type layer 2 and the first P-type layer 3, and the second P-type layer 4 and the second N-type layer Nitrogen is added to the vicinity of the second PN junction 8 at the boundary between the first and second PN junctions 7 and 5, so that the first and second PN junctions 7 and 8 emit red and green light, respectively, when forward biased.

In the process shown in FIG. 1B, Zn is diffused from the surface of the light-emitting substrate 6 except for the central part, and
Mold layers 9, 10 are provided. At this time, the diffusion depth reaches the second P-type layer 4. Note that the diffusion temperature is about 800° C., and the first and second PN junctions 7 and 8 are not damaged by this temperature.

In the step of FIG. 1C, from the surface of the light emitting substrate 6,
Etching is performed along each boundary between the second N-type layer 5 and the third and fourth P-type layers 9 and 10 to form separation grooves 11 and 12 that reach the second P-type layer 4.

In the step of FIG. 1D, on the fourth P-type layer 10,
A fifth P-type layer 13 made of GaAs _1-x P _x (gallium arsenide phosphide, o≦x≦1), a sixth P-type layer 14 and a third N-type layer 15 made of GaAs (gallium arsenide) are formed by molecular beam epitaxy. Formed by growth method. That is, the light-emitting substrate 6 and vapor deposition sources of Ga, As, and P are arranged in an ultra-high vacuum of about 10 ^-11 Torr, and the substrate 6 is placed in an ultra-high vacuum of about 10 -11 Torr.
By maintaining the temperature at 500 to 600°C and controlling the temperatures of each of the vapor deposition sources mentioned above, an epitaxially grown layer having a desired composition can be obtained. As mentioned above, the temperature of the substrate 6 is low, so the first and second PN junctions 7 and 8 are not damaged even in this process. The fifth P-type layer 13 contains almost no As at the initial stage of growth, contains As which increases and P which decreases as it grows, and almost no P at the final stage of growth. Therefore, the third PN junction 16 formed by the sixth P-type layer 14 and the third N-type layer 15 emits infrared light, and the fifth P-type layer 13
It acts as a buffer layer that alleviates the difference in crystal structure between the mold layer 14 and the mold layer 14 .

In the step of FIG. 1E, the substrate 1, the second N-type layer 5,
Ohmic electrodes 17, 18, 19, and 20 are provided on each surface of the third P-type layer 9 and the third N-type layer 15, respectively, and a phosphor 21 that generates blue light by excitation with infrared light is further provided on the upper surface of the third N-type layer 15. After coating, the device is completed. Furthermore, as the phosphor 21, YF ₃ :Yb:Tm
(yttrium fluoride: ytterbium: thulium) is preferred.

As is now clear, the completed device uses the ohmic electrode 19 as a common positive electrode and the other ohmic electrode 1.
By using 7, 18, and 20 as negative electrodes, red,
Selectively emits green and blue light.

FIG. 2 shows another embodiment of the present invention, in which the process of A in the figure is similar to the process of FIG.
On the substrate 30, a first N-type layer 31, a first P-type layer 32,
A second P-type layer 33 and a second N-type layer 34 are sequentially stacked, and first and second PN junctions 35 for red and green light emission,
A light emitting substrate 37 including 36 is formed.

In the process shown in FIG. 2B, from the surface of the light emitting substrate 37,
A third P-type layer 38 that reaches the second P-type layer 33 through selective diffusion of Zn, a second N-type layer 34 and a third P-type layer 3
A separation groove 39 that reaches the second P-type layer 33 is provided along the boundary with the second P-type layer 33 .

In the step of FIG. 2C, the first
A third N-type layer 40 made of GaAs _1-x P _x and ZnSe are grown by molecular beam epitaxial growth similar to the process shown in Figure D.
A fourth N-type layer 41 made of (zinc selenide) is sequentially laminated. Note that the third N-type layer 40 is the 5P layer in FIG.
Like the mold layer 13, it functions as a buffer layer. Also, the 4th N
The temperature of the base 37 when forming the mold layer 41 is preferably 300 to 400°C.

In the process shown in FIG. 2D, the surface of the fourth N-type layer 41 is
An insulating film 42 such as SiO ₂ (silicon dioxide) is formed by the CVD method, and then ohmic electrodes 4 are formed on the substrate 30, the second N-type layer 34, and the third P-type layer 38, respectively.
3, 44, and 45 are provided, and further on the insulating film 42.
The MIS electrode 46 is formed to complete the device. still
The MIS electrode 46 forms an MIS structure together with the fourth N-type layer 41 and the insulating film 42, and this structure has a blue light emitting function.

In the completed device, red and green lights are generated by using the ohmic electrode 45 as the common positive electrode and the other ohmic electrodes 43 and 44 as the negative electrode, and also using the ohmic electrode 44 as the negative electrode and the MIS electrode 46 as the positive electrode. This causes blue light emission.

In each of the above embodiments, the light emitting substrates 6 and 37 have both red and green light emitting functions, but if unnecessary,
Of course, it is fine to use only one of them.

Thus, according to the present invention, a red and/or green light emitting layer is sequentially formed by a liquid phase epitaxial growth method, and an additional light emitting layer contributing to blue light emission is formed sequentially by a molecular beam epitaxial growth method which can be performed at low temperatures. Therefore, the red and/or green light emitting layer is not damaged during the formation of the additional light emitting layer, and the structure extracts blue light.
A combination of P-type and N-type gallium arsenide laminate and phosphor, or one conductivity type zinc selenide.
By using the MIS structure, blue light emission is realized in addition to red and green light emission. Furthermore, by combining the liquid phase epitaxial growth method and the molecular beam epitaxial growth method, the device can be completed in a shorter time than when all the light emitting layers are formed by the molecular beam epitaxial growth method.

[Brief explanation of the drawing]

FIGS. 1 and 2 are step-by-step side views showing an embodiment of the present invention. 6,37...Light-emitting substrate.

Claims (1)

[Claims] 1. Includes a PN junction that emits red and/or green light,
A step of forming an additional light-emitting layer contributing to blue light emission by molecular beam epitaxial growth on the light-emitting substrate on which the P-type and N-type semiconductor layers forming the PN junction are formed by liquid phase epitaxial growth. The additional light-emitting layer is a laminate of P-type and N-type gallium arsenide layers that emit infrared light, and a phosphor that generates blue light when excited by infrared light is provided on the gallium arsenide layer. A method for manufacturing a solid-state light emitting device characterized by: 2 Including a PN junction that emits red and/or green light,
A step of forming an additional light-emitting layer contributing to blue light emission by molecular beam epitaxial growth on the light-emitting substrate on which the P-type and N-type semiconductor layers forming the PN junction are formed by liquid phase epitaxial growth. A method for manufacturing a solid-state light emitting device, characterized in that the additional light emitting layer is a zinc selenide layer of one conductivity type, and an insulating film and an electrode are sequentially deposited on the zinc selenide layer.