JPS5812381A - Gan blue light emitting element - Google Patents

Abstract

PURPOSE:To make a GaN blue light emitting element to have narrow half- width of emitting light making 440nm as the center of wave length while enhancing intensity of emitting light by a method wherein zinc phosphide is used as impurities to be doped in a GaN single crystal layer at the GaN blue light emitting element. CONSTITUTION:The GaN layer consisting of undoped GaN single crystal is formed on the main face of a sapphire (Al2O3) substrate having the (0001)C face as one main face, and a doped layer doped with acceptor impurities, zinc phosphide (ZnP2 or Zn2P3), for example, is formed on the GaN layer thereof. When zinc phosphide is used as impurities like this way, light having narrow half-width can be observed making 440nm as the peak value. Moreover intensity of emitting light at emitting light wave length of 440nm is extremely high.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a Gap (Gallium Nitride) color emitting element.Currently, visible sensing elements are capable of emitting red, green, yellow and orange colors.
t, has been put into practical use.Recently, 1
A multi-color developing element that can sequentially change the developing color from red to the edge has been developed and is being put into practical use.However, regarding the color developing element that emits blue, one of the three primary colors of the party, Although it has been studied for a long time, it has not yet reached the stage where it can be put into practical use.

The materials for the blue detection element are frame, GaN, 810, and Z.
Examples include n8e and Zn8.

Among them, GaN has had the highest detection efficiency at the research stage so far and is seen as promising.

Figure 1 shows a conventional Ga1i'ff color light emitting device, +1
) - sapphire (4) whose soil surface is (0001)ell
420 substrate, (2) is a GaN layer made of undoped GaH single crystal formed on the main surface of the substrate (1), (3
) is [G! A doped layer (4) is a metal electrode formed on the doped layer (13).

Usually, the above GaN layer (2) is formed by G&01-MH5 (gallium chloride-ammonia) at a high temperature of 900 to 1100'C.
It is obtained by trap vapor phase growth using the direct reaction t-system.

At this time, the GILN layer (2) has a Φ Yaria concentration of 101
s~1Q ''/dl'' shows strong Ma1 conduction T
However, this is because when the growth temperature of Cn and [()aN is high, nitrogen is removed from the GaN crystal once grown and vacancies are generated.

In addition, the acceptor impurity doped in the doped layer 3) substitutes at the position of the Ga atom and acts as an acceptor, and the doped layer 13) serves as a semi-insulating back gate layer to compensate for the vacancies.・The GaM blue detection element is a metal electrode 14), B51
1lI8! consisting of layer (3) and Ga11 layer 12). lI
It has a structure of 4K (41-G a M layer) of metal electrodes, and by applying 7 passes between 21 and 21 layers, it is possible to obtain true color development.

@2aill shows a GaN vapor phase growth device,
] 1 is connected to one side 11i with j [1 to 3rd gas inlet (13 to α
- is a quartz growth furnace provided with a gas outlet on the surface opposite to the side surface, US is the first gas inlet pipe installed in the first gas inlet, and aη is the second gas inlet pipe. 112 gas introduction tubes that pass through the gas introduction port 0 of the growth furnace 11υ and one end of which reaches approximately the inside of the growth furnace 11υ, and the end of the introduction tube fin inside the growth furnace 11υ is connected to the gallium mounting part. It has become. 19
[Penetrate through the third gas inlet port a.]

One end of it is the third gas introduction pipe that reaches approximately the middle of the growth furnace value υ, and outside of the growth furnace I in the third gas introduction pipe part, an impurity board ■ is placed. Gas outlet QS
Gas exhaust pipe attached to the gallium mounting part α above the stile
A gallium boat placed within l.

＠ is a substrate mounting table placed in the growth furnace and extending from near the end of the gallium mounting part to the gas exhaust port a9 side.
(2) is a heating device installed around the growth furnace (2) that controls the heating of the rt, growth furnace (1), and gas inlet areas;
Table 24) Heat the vicinity of the gallium boat (2) in %
It consists of an I2 heater (24!I) and a third heater (240) that heats the vicinity of the impurity boat (1).

A general G&N vapor phase growth method using the above-mentioned vapor phase growth apparatus will be explained below.
The method for growing the first layer (2) will be explained.

Place the sapphire substrates on the gallium boat so that the surface becomes the (0001) 0 plane on the Ga (Gallium>4, M plate), and 2 heaters (24mm) and (24B) were heated to 900~ which is the growth temperature of sapphire base [(to) tea H]
GEL is held at 1100'C and GEL at 700-900'C, which is the melting temperature of G&, respectively.

In this state, N2 (
When Hal (hydrochloric acid) gas is sent into the growth reactor qv using Nitrogen (nitrogen) gas as a carrier gas, the above Ficl gas reacts with Ga+HoJ-*Gacl+%H2 on the gallium boat, producing GaCl (gallium chloride). is,
Growth reactor +1υrcEIkG a c l is delivered.

Inside the growth reactor, the gas inlet pipe C of eacJ[11!1
NH using N2 gas sent from I8 as carrier gas
A reaction of &(7 mm air) gas and GaeJI÷NBA-eGaN+Ho/+H2 occurs to generate GaNt-. The Ga wing is made of a sapphire substrate (
Since E) is maintained at 900 to 1100'C, a single crystal is grown on the 7-Iyer substrate (to). After the completion of 1 reaction, N2 gas other than Ga11, Hop gas, and ■2 gas are discharged. Next, a method for growing the high resistance layer doped with a 7-ptamer impurity, that is, the doped layer (3) in FIG. 1, will be explained.

The impurity is placed on the impurity board (A), and then the third heater (24c) of the heating device is controlled to maintain the melting temperature tc of the impurity, and the gas introduction pipe of 5I3 (L9 is connected to the growth furnace). N2 gas is fed into the tiυ as a carrier gas.In addition, in the above growth apparatus, each gas fed into the gas introduction pipe Qet1M of gl, I!2 and the first, g2
The impurity (2) that has become steam from the temperature side gas inlet pipe a9 of the heater (24 &) (24B) is M! Growth furnace a by gas
These impurities are sent to the sapphire substrate (towards).
An impurity doped layer 131 # is grown by replacing the pseudo GaM single crystal having a length of 5E above. Conventionally, Zn (zinc) t- was used as an impurity to be doped into the doped layer 131.

However, the case where Zn is used as an impurity is refused.

If the amount of doping is too large, there is a risk that the detected level will become green, orange, red, etc. other than the background color, and if doping is refrained to bring the luminescence level to the blue level, the Ga11 layer 12) will become a strong Bl as described above. Because there is a doped layer 13
) had to have a high resistance.

The present invention has been made in view of the above points.A feature of the present invention is that a zinc phosphide (ZnP2, or t!Zn2PB) compound is used as the impurity.

*sWA is an experiment that shows the relationship between the emission wavelength and emission intensity when Zn and zinc phosphide are used as doping impurities in the doped layer (3) in the GaN blue light-emitting device shown in Figure 1. The result is 69. The graph shows the characteristics when the graph is solid.

Furthermore, the growth conditions for the eaN single crystal at this time.

Lisa 7 Aiya substrate temperature station...960℃~980'CTa
cit)#l amount -10~20 Cc/winl
ll o51 amount...1.3~2.0 l/wi
Flow rate of N2 as carrier gas for nreal -1,0 to 1,51/m1
Flow rate of N2 as carrier gas for n1■ = 3.5 to 5.7 l/winG
The temperature of a is -850℃tso'c, and the carrier concentration f of GaM grown under such conditions is about 10
/(It was II.

Also, what are the doping conditions for impurities?

Impurity storage l...425°C Flow rate of N2 for sending out impurities...11/win. Regardless of whether den or zinc phosphide is used as an impurity under these conditions, the luminescence level of the Ga11-emitting element is a critical condition.

19 When the impurity temperature is 425° C. or higher #C, the emission wavelength becomes 440 nm or higher, making it difficult to obtain colored luminescence.

When the impurity temperature is below 450°C, the luminescence level becomes blue, but in this case, if Zn is used as an impurity, a high-resistance doped layer cannot be obtained. If the partial pressure P of zinc valine in the growth reactor Al to obtain the luminescence level is 10 to 10 atmK, assuming that the pressure inside the growth reactor is t-1 atm.
When the impurity temperature is 450°C, the above N
The above partial pressure is satisfied when the flow rate of No. 2 is approximately 1 e/mtn.

As is clear from the @3 figure et al. above, when Zn is used as an impurity, the blue emission wavelength is centered around 440 nm,
The element that has a broad peak from 50nm to 480nmrc is 1! However, when zinc phosphide was used as an impurity, a narrow band around half the maximum was observed with the peak set at 440 nm. We obtained the result that the detected strong Jf at the emission wavelength of 440 nm is stronger when zinc phosphide is used as an impurity.The reason for this is that when zinc phosphide is used as an impurity, GaN
This is because phosphorus reduces the Il& of the nitrogen position #/c substituted i'Lyi1 and acts as an effective isoelectronic trap.

This is because Zn replaces gallium and works as an effective acceptor, as in the past.

[If the above zinc phosphide is used, phosphorus is at the nitrogen position 1It
Since the FIcR is converted and the concentration of nitrate and ions is reduced, a semi-insulating high resistance layer can be obtained with a smaller amount of Zn than when doping only Zn.

In other words, according to the inventor's experiments, when zinc phosphide is used as an impurity, a high resistance layer having a blue light emission level can be obtained at an impurity temperature of 400° C. to 425° C. Therefore, the impurity temperature is not strictly controlled compared to when Znl is used as an impurity.

As is clear from the above explanation, according to the present invention, 440n
Has a narrow half-maximum center wavelength with m as the center wavelength

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional GaN blue light emitting device.
Figure 3 is a cross-sectional view showing a typical GaN vapor phase growth apparatus, and Figure 3 is a characteristic graph showing the light emitting characteristics of the conventional GILN color-producing color light-emitting element and a GaN blue light-emitting element.

Claims (1)

[Claims] 11) A single crystal sapphire (iJ2os) substrate, a GaN single crystal layer deposited on the substrate, and a doped layer formed by doping the surface of the crystal layer with an impurity. Ga consisting of the doped layer surface and the #C formed metal electrode.
A GaM'l1 color generating element characterized in that zinc intercalation is used as the impurity in the llfi generating element.