JPH0410667A - Light-emitting element of gallium nitride-based compound semiconductor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a gallium nitride compound semiconductor light emitting device that emits white light.

[Prior art]

Conventionally, blue light emitting diodes using GaN-based compound semiconductors are known. The GaN-based compound semiconductor is attracting attention because it has high luminous efficiency due to direct transition, and because it emits blue light, which is one of the three primary colors of light. A light emitting diode using such a GaN-based compound semiconductor is produced by growing an n-layer made of an n-type GaN-based compound semiconductor on a sapphire substrate directly or with a buffer layer made of aluminum nitride interposed therebetween. layer i
It has a structure in which an i-layer made of a type of GaN-based compound semiconductor is grown (Japanese Patent Application Laid-open No. 119196/1983,
(Japanese Unexamined Patent Publication No. 188977/1983).

[Problem to be solved by the invention]

However, zinc is used as a doping element in one layer of the light emitting diode having the above structure. For this reason, the emitted light color is fixed to blue, and other colors such as white or red cannot be emitted. Furthermore, there is no known light emitting diode that emits the three primary colors of light, blue, green, and red, with a single bulb. Therefore, when constructing a color display in which three pairs of dots display one point, it is difficult to integrate the three pairs of dots on the same substrate. Therefore, an object of the present invention is to obtain red light emission in addition to the blue light that GaN-based compound semiconductors normally emit.

[Means to solve the problem]

The present invention relates to an n-type gallium nitride compound semiconductor (Aj2
XGa1-XN;
In a gallium nitride compound semiconductor light emitting device having an i-layer consisting of N;
i), the ratio of silicon doping density to zinc doping density is 1/1000 or more 1720
It is characterized by being 0 or less.

[Operation and effects of the invention]

In the present invention, red light emission can be obtained by using zinc (Zn) and silicon (S) as doping elements for the i-layer and by setting the ratio of silicon to zinc to be 1/1000 or more and 1/200 or less. Ta.

【Example】

The present invention will be described below based on specific examples. First, a light emitting diode manufacturing apparatus according to this embodiment will be described. FIG. 2 is a sectional view of a vapor phase growth apparatus for manufacturing a gallium nitride light emitting diode of the present invention. The quartz tube 10 is sealed with an OIJ song 5 at its left end and abuts against the flange 14, and is fixed to the flange 14 at several points using bolts 46, 47, nuts 48°, 49, etc. using a buffer material 38 and a fixture 39. ing. The right end of the quartz tube 10 is sealed with an O-ring 40 and fixed to the flange 27 with screw fixing devices 41 and 42. An inner chamber 11 surrounded by a quartz tube 10 is provided with a liner tube 12 for guiding a reaction gas. One end 13 of the liner tube 12 is connected to a retaining plate 17 fixed to the flange 14.
The bottom portion 18 of the other end 16 is held on the quartz tube 10 by a holding leg 19. As shown in FIG. 7, the planar shape of the liner tube 12 widens toward the downstream, and the cross section of the liner tube 12 perpendicular to the long axis (X-axis) of the quartz tube 1o is shown in FIGS. 3 to 6. like,
It varies depending on the position in the X-axis direction. That is, the reaction gas is
It flows in the axial direction, but on the upstream side of the gas flow, it is circular as shown in Fig. 2, and as it advances downstream (X-axis stop direction), it expands in the long axis direction with the Y-axis direction as the long axis. It has an elliptical shape that is reduced in the short axis direction, and at position A, which is slightly upstream where the susceptor 20 is placed, it is elliptical in the vertical direction (
It has an oblate elliptical shape that is thinner in the Z-axis direction and longer in the Y-axis direction. The length of the opening in the Y-axis direction in the IV-IV cross-sectional view shown in FIG. 5 at position A is 7 cm, and the length in the Z-axis direction is 1°2 am. On the downstream side of the liner tube 12, a sample mounting chamber 21 having a rectangular cross section perpendicular to the X-axis in which the susceptor 20 is mounted is integrally connected. A susceptor 20 is placed on the bottom 22 of the sample placement chamber 21 . The susceptor 20 has a rectangular cross section perpendicular to the X-axis, but its upper surface 23 is gently inclined in the Z-axis stopping direction with respect to the X-axis. A sample, that is, a rectangular sapphire substrate 51 is placed on the upper surface 23 of the susceptor 20, and the gap between the sapphire substrate 51 and the upper tube wall 24 of the liner tube 12 facing it is 12 mm at the upstream portion and 12 mm at the downstream portion. Part 4mm
It is. An operating rod 26 is connected to the susceptor 20, and by removing the flange 27 and using the operating rod 26, the susceptor 20 on which the sapphire substrate 51 is mounted can be placed in the sample mounting chamber 21, or when crystal growth is finished. , the susceptor 20 can be taken out from the sample placement chamber 21. Furthermore, a first gas pipe 28 and a second gas pipe 29 are open on the upstream side of the liner pipe 12. The first gas pipe 28
It is located inside the gas pipe 29, and both pipes 28 and 29 are coaxial and have a double pipe structure. A large number of holes 30 are formed around the portion of the first gas pipe 28 that protrudes from the second gas pipe 29, and a large number of holes 30 are also formed in the second gas pipe 29. Then, the reaction gas introduced through the first gas pipe 28 is blown into the liner pipe 12, where it is first mixed with the gas introduced through the second gas pipe 29. The first gas pipe 28 is connected to a first manifold 31 and the second gas pipe 29 is connected to a second manifold 32. The 17th second hold 31 has a carrier gas supply system ■, a trimethyl gallium (hereinafter referred to as "TMG") supply system J, and a trimethyl aluminum (hereinafter referred to as r
diethylzinc (hereinafter referred to as r) in the supply system of
DEZ) supply system and a silane (SIH4) supply system M are connected. The second manifold 32 is connected to an NH, supply system H and a carrier gas supply system (2). A cooling pipe 33 for circulating cooling water is formed on the outer periphery of the quartz tube 10, and a high frequency coil 34 for applying a high frequency electric field is disposed on the outer periphery of the cooling pipe 33. Further, the liner pipe 12 is connected to the outer pipe 35 via the flange 14.
The carrier gas is introduced from the external pipe 35. Further, an introduction pipe 36 extends from the outside into the sample holding chamber 21 by passing through the flange 14 from the side.
A thermocouple 43 and its conductor wire 44 for measuring the temperature of the sample are installed inside.
45, and is configured so that the sample temperature can be measured from the outside. With this device configuration, the mixed gas of TMG, TMA, H2, DEZ, and silane led through the first gas pipe 28 and the mixed gas of NH3 and H2 led through the second gas pipe 29 are mixed. The mixed reaction gas is mixed near the outlet of the tube, and the mixed reaction gas is guided by the liner tube 12 to the sample holding chamber 21 and passes through the gap formed between the sapphire substrate 51 and the upper tube wall 24 of the liner tube 12. At this time, the flow of the reaction gas on the sapphire substrate 51 becomes uniform, and a high-quality crystal with little location dependence grows. When forming an n-type All, Ga, -XN thin film, the supply of DEZ and silane is stopped and the first gas pipe 2
8 and the second gas pipe 29. When forming an i-type A 1 x Ga 1-XN thin film, DEZ and silane are supplied to the first gas pipe 28 and The respective mixed gases may be flowed out from the second gas pipe 29. When forming an i-type A 12 xG a + -XN thin film, DEZ and silane are placed on the sapphire substrate 51.
The dopant element grows as A
IlxG a + -XN is doped to obtain i-type A Il xG a + -XN. Next, a method for manufacturing the light emitting diode 50 having the configuration shown in FIG. 1 using this apparatus will be described. First, a single-crystal sapphire substrate 51 having an a-plane main surface that has been cleaned by organic cleaning and heat treatment is attached to the susceptor 20 . Next, the pressure in the reaction chamber 11 is set to lx 1O-5 Tor
After reducing the pressure to
2, the sapphire substrate 51 was heated to 1100°C.
was vapor-etched. Next, the temperature was lowered to 400°C, H2 was pumped through the first gas pipe 28 at 10 I2/min, H2 bubbled in TMA at 15°C was pumped at 5011 Z min, and H2 was pumped through the second gas pipe 29 at 1/min.
01 min, NH was supplied at 10β/min for 2 min. In this growth step, a buffer layer 52 of AIN was formed to a thickness of approximately 500 nm. Next, when 2 minutes have elapsed, the supply of TMA is stopped, the temperature of the sapphire substrate 51 is maintained at 1150°C, and H2 is bubbled through the TMG at -15°C at 101/min from the first gas pipe 28. 200 nl/min of silane (Sil14) diluted to lppm with H2 for 1.7 min, H2 from the second gas pipe 29 at 10β/min, NH3 at 10β/min.
A high carrier concentration n-layer 53 made of GaN with a film thickness of about 2.5 mm and a carrier concentration of 2×10'8/c++t was formed by supplying it for 15 minutes. Subsequently, the temperature of the sapphire substrate 51 is maintained at 1150° C., and H is similarly supplied from the first gas pipe 28 and the second gas pipe 29.
2 was bubbled in TMG at -15°C at a rate of 100 mI2/min and NH3 was supplied for 20 minutes at a rate of 101/min.
Low carrier concentration n-layer 54 made of GaN with Q”/crd
was formed. Next, the sapphire substrate 51 was heated to 900°C, and similarly,
H2 from the first gas pipe 28 and the second gas pipe 29, respectively.
H2 bubbled in TMG at -15°C at 1011/min at 10On+j! H 2500mj? bubbled in DEZ at 5℃ for 7 minutes. 7 minutes, ippm on H2
10ml 1/min of silane (SIH4) diluted with NH
3 was supplied for 1 minute at a rate of 1017 minutes to form one layer 55 made of GaN to a film thickness of 750 mm. At this time, 1 layer 5
The density of zinc in 5 is 1 xlQ20/cn! in,
The density of silicon was 1×10 17 /Cl 11 . In this way, a multilayer structure as shown in FIG. 8 was obtained. Next, as shown in FIG. 9, a SiO□ layer 61 was formed to a thickness of 100 on the first layer 55 by sputtering. Next, a photoresist 6 is applied on the 5th layer 02 layer 61.
2 was applied, and the photoresist 62 was formed by photolithography into a pattern in which the photoresist at the electrode formation site for the high carrier concentration n layer 53 was removed. Next, as shown in FIG. 10, the 5in2 layer 61 not covered by the photoresist 62 was removed using a hydrofluoric acid etching solution. Next, as shown in FIG. 11, one layer 55 of the photoresist 62 and the SiO
, a low carrier concentration n layer 54 below it, and a high carrier concentration n layer 54
A part of the upper surface of the layer 53 was heated to a vacuum of 0°04 Torr, a high frequency power of 0.44111/cil, and a flow rate of 10 cc/min.
After etching with Cβ2F2 gas, dry etching was performed with Ar. Next, as shown in FIG. 12, the SlO□ layer 61 remaining on the first layer 55 was removed with hydrofluoric acid. Next, as shown in FIG. 13, an Aβ layer 63 was formed on the entire surface of the sample by vapor deposition. Then, a photoresist 64 was coated on the A1 layer 63, and the photoresist 64 was patterned into a predetermined shape by photolithography so that electrode portions for the high carrier concentration n layer 53 and the first layer 55 remained. . Next, as shown in FIG. 13, using the photoresist 64 as a mask, the exposed portion of the lower An layer 63 is etched with a nitric acid-based etching solution, the photoresist 64 is removed with acetone, and the high carrier concentration n layer 53 is etched. Electrode 8.1 layer 55
The electrode 7 was formed. In this way, Mis (Metal-
It is possible to manufacture a gallium nitride-based light emitting device with a 1nsulator-semiconductor structure. When the light emitting intensity of the light emitting diode 10 manufactured in this way was measured, it was 0.1 mcd. Further, the electroluminescence intensity of this single layer 55 was measured. The results are shown by curve B in FIG. That is, the EL intensity at a wavelength of 480 nm (blue) and wavelength 550 nm (green) is small, and conversely, the EL intensity at a wavelength of 700 nm (red) is large.Furthermore, the color perceived by the human eye of the light emitting diode was red. In addition, the zinc density in one layer 55 is 5×10”/
cnt to 3X1021/cnt, and the ratio of silicon density to zinc density in that range is 1/20.
A plurality of light emitting diodes with a ratio of 0 to 1/1000 were manufactured. Then, the electroluminescence intensity of one layer 55 of the light emitting diode was measured. The measurement results are the first
The curve was almost similar to curve B in Figure 4. Also, the color of those light emitting diodes as perceived by humans was red. For comparison, the zinc density in one layer 55 is
0”/cn!, silicon density 1.5 x 10”
/cJ was manufactured. Then, the electroluminescence intensity of one layer 55 of the light emitting diode was measured. The measurement result was curve A in FIG. In curve A, compared to curve B, the EL intensity at a wavelength of 480 nm (blue) is larger, the BL intensity at a wavelength of 550 nm (green) is about the same, and the EL intensity at a wavelength of 700 nm (red) is higher. The strength is reduced. And the spectrum is spread throughout. The emitted light color of this light emitting diode that was visually recognized by the human eye was white. Further, the density of silicon in one layer 55 is determined by the density of zinc I
X 10. ”/ 1/100 to 1/2 for cn+
Light emitting diodes were manufactured in the same manner by changing the ratio by 0.00. The electroluminescence intensity of the first layer 55 was measured and was similar to curve A in FIG. 14. Further, the light emitted from the light emitting diode was white. In addition, the zinc density in one layer 55 is 5X10'97cnt
Light-emitting diodes were manufactured in the same manner by changing the silicon density at a ratio of 1/20 to 1/100 with respect to the zinc density. Electroluminescence intensity of the i layer 55 was measured, and a curve almost similar to curve A in FIG. ”／c
++t, and a light emitting diode not doped with silicon was manufactured. Then, the electroluminescence intensity of one layer 55 of the light emitting diode was measured. The characteristics shown by curve C in FIG. 14 were obtained. That is, curve B
Compared to [! However, the BL intensity at a wavelength of 550 nm (green) appears at the same level, and conversely, the BL intensity at a wavelength of 700 nm (red) is significantly smaller. The emitted light color of these light emitting diodes recognized by humans was blue. From the above, the following can be concluded. (1) When one layer 55 is doped only with zinc, the light emitting color of the light emitting diode is blue. (2) One layer 55 is doped with zinc and silicon, and the doping amount of silicon is 1/20 in proportion to the zinc density.
When the amount is relatively small in the range of 0 to 1/1000, the light emitted by the light emitting diode is red. (3) One layer 55 is doped with zinc and silicon, and the doping amount of silicon is 1/10 in proportion to the zinc density.
When the amount is relatively large (0 to 1/200), the light emitted by the light emitting diode is white. In the above example, silane was used as a raw material for silicon, but tetraethylsilane ((C211s>48t :T
ES+) may also be used.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the structure of a light emitting diode according to a specific embodiment of the present invention, FIG. 2 is a block diagram showing an apparatus for manufacturing the light emitting diode, and FIGS. 3 to 6 are 7 is a plan view of the liner tube used in the device, FIGS. 8 to 13 are sectional views showing the manufacturing process of the light emitting diode, and FIG. 14 is the light emitting diode. FIG. 15 is a measurement diagram showing the results of electroluminescence measurement of the i-layer. FIG. 15 is a measurement diagram showing the results of SIMS analysis of the i-layer. 10° light emitting diode 1゛Sapphire substrate 2-buffer layer 3°°high carrier concentration n layer 4゛low carrier concentration n layer 5・-i layer 7.8-electrode

Claims (1)

[Claims] N-type gallium nitride compound semiconductor (Al_XGa_
1_-_XN; including X=0) and an i-type gallium nitride compound semiconductor (Al_XGa_1_-
In a gallium nitride-based compound semiconductor light emitting device having an i-layer consisting of Zn; The ratio to the doping density is 1/1000 or more and 1/
200 or less.