JPH036872A - Light emitting device using diamond and its manufacture - Google Patents

Abstract

PURPOSE:To avoid degradation of a light emission luminance by a method wherein a diamond layer is formed on a P-type silicon substrate and an N-type silicon carbide or silicon film is provided on the diamond layer. CONSTITUTION:A diamond layer 2 composed of a B-doped diamond layer 2-1 and a non-doped or S-, Se- or Te-doped diamond layer 2-2 is formed on a P-type silicon substrate 1. Further, an N-type silicon film 3 is formed on the diamond layer 2. Further, an N-type conductive film is formed and subjected to a thermal treatment to make the lower junction of silicon react with the upper part of diamond to produce silicon carbide. VIb dopant and N-type dopant are mixed in the silicon carbide film and, further, the silicon film part on it is doped with N-type dopant only. Then electrode members 4 and 5 are applied to the surface by a vacuum evaporation method and a sputtering method.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Application of the Invention" The present invention relates to a visible light emitting device using diamond and a method for manufacturing the same.

"Prior Art" Regarding light emitting elements, red light emission has already been achieved more than 10 years ago by using a 1-2 compound semiconductor such as GaAs. However, this light emitting element is red,
It is extremely difficult to produce blue and green colors, and it has been completely impossible to produce continuous visible light such as white light using crystalline materials.

Attempts to make light-emitting devices using diamond have already been demonstrated by the present inventor, for example, in Patent Application No. 146 filed in 1982.
No. 930 (filed on September 17, 1982).

Considering the size of the market for light-emitting devices, diamond has the advantages of being heat resistant and extremely chemically stable, and is also made from carbon, an inexpensive material.
The potential for its industrial mass production is extremely large.

However, it is difficult to make light-emitting devices using this diamond stable.
Moreover, no method for producing it with high yield or the structure necessary for it has been shown so far.

"Conventional Disadvantages" The present invention was made in order to construct a visible light emitting device using diamond, increase its yield, and increase luminous efficiency.

The present inventor investigated what kind of luminescent center is in a conventional diamond. They also investigated the drawbacks that until now, when a large current was applied to the pair of electrodes that make up the device, a large amount of heat was generated and the device did not emit sufficient visible light. As a result, the following facts were found.

Since the Schottky junction does not have a sufficiently stable function, an abnormally high voltage must be applied. Furthermore, the degree of Schottky junction in the voltage varies from element to element, and a high manufacturing yield cannot be expected.

In addition, although it is easy to create the ■ type (intrinsic) and P type conductivity types of diamond, it is extremely difficult to create the N type conductivity type, and as a result, it is difficult to construct a PIN junction or PN junction using only diamond. It was difficult.

``Object of the Invention'' The present invention has been made to eliminate such drawbacks. That is, silicon or silicon carbide having an N-type conductivity is provided in a single layer or in multiple layers between an electrode disposed on the upper side and a diamond having a ■-type or P-type conductivity.

In particular, this buffer layer material also had the effect of preventing local abnormal chemical reactions between the electrode material and the diamond material from proceeding. Then, by efficiently injecting charge into the luminescent source in the diamond, recombination occurs between the luminescent centers and in the band f.
Bl (between valence bands) or between a luminescent center and a band (conduction band or valence band).

``Structure of the Invention'' The present invention comprises a P-type diamond on a substrate such as a P-type semiconductor or conductor, or a substrate having an insulating surface, and an N-type silicon carbide or silicon monomer on the upper surface of the diamond. One or more electrodes are provided via a layer or multiple layers of Ji (hereinafter also referred to as buffer layer). In the case of one electrode, the substrate is used as a conductor, and visible light is generated by passing a pulse, direct current, or alternating current between the substrate and the electrode. When a plurality of electrodes are formed, diamond is provided on a substrate having an insulating surface, and a similar current is passed between the plurality of electrodes on the diamond to provide a light emitting device, for example, a visible light emitting device. N-type silicon, silicon carbide, or a multilayer film of these is provided between this upper electrode and the diamond, and as a result, the electrode material and diamond are directly connected as an N-type conductor layer on the P-type or I-type diamond. By avoiding close contact, reliability was improved under long-term actual usage conditions.

That is, the structure is one in which a P-type (silicon substrate)-P or I (diamond)-N (silicon carbide, silicon, or silicon on silicon carbide) bond is stably produced.

Furthermore, in the present invention, Vtb group impurities are added to this diamond as an additive in order to more effectively generate blue light emission. That is, S (sulfur), Se (selenium), Te (
Elements selected from tellurium (tellurium) were added. Further, a compound of carbon and oxygen such as methanol (CI, OH) was used for diamond synthesis.

Specifically, BtS+ 1Izse, 1IzTe+ (
C113) zS+ (CHi) zse.

(CL) zTe was added during diamond film formation.

Another method is 0 + S + Se l T
e may be added after forming the diamond film by ion implantation. In this way, damage can be created in the diamond and impurities can be added at the same time, making it possible to create more recombination centers or luminescent centers.

When this ion implantation method is used, the damage remains even after annealing in the atmosphere, for example at 300 to 600°C, and the strain energy in an atomic sense is only alleviated, which increases luminous efficiency. be able to.

As a result, the interface between the electrode and the diamond is chemically stabilized, and current flows through the diamond, resulting in interband transitions, transitions between bands and recombination centers or luminescent centers, or transitions between recombination centers or luminescent centers. The idea is that recombination of carriers occurs due to the transition between the two layers, and as a result, visible light is emitted according to the energy band interval (gap) of the recombination.

In particular, visible light can produce blue and green colors depending on the transition band. Furthermore, by creating an energy level at the recombination center between multiple bands, it is also possible to create continuous light such as white light.

The present invention will be described below according to examples.

"Example 1" In the present invention, diamond was produced on a silicon semiconductor or a metal conductor using a magnetic field microwave CVD apparatus shown in FIG. The method of forming a diamond film using this magnetic field microwave CvD apparatus is disclosed in Japanese Patent Application No. 61-292859 (thin film forming method (filed on December 8, 1986) filed by the present inventor). The outline is shown below.

A semiconductor substrate doped with P-type at a high concentration was immersed in an alcohol mixture containing diamond particles, and ultrasonic waves were applied for 1 minute to 1 hour.

Then, many minute damages can be formed on this semiconductor substrate. This damage can serve as a source of seeds for subsequent diamond formation. This substrate (1) was placed in a magnetic field microwave plasma CVD apparatus (hereinafter also simply referred to as a plasma CVD apparatus). This plasma CV
Device D supplies microwave energy at a frequency of 2.45 GHz up to 10 KW to a reaction chamber (1) through a microwave oscillator (18), attenuator (16), and quartz window (15).
9) can be added. Also, the magnetic field (17), (
Using a Helmholtz coil at 17°), a maximum of 2.2 KG (kilo Gauss) was applied to create a resonance surface of 875 Gauss. The board (1) inside this coil was placed in a holder (13) with a board press (14). Further, the position within the reactor was adjusted using the substrate position moving mechanism (12).

Further, the vacuum was drawn down to 101 to 10-' torr.

After this, methyl alcohol (CH301
1) or alcohol (22) such as ethyl alcohol (CJsOH) with hydrogen (21) to a volume of 40 to 200 χ (1
00 volume% corresponds to CHzOH:Hz=1:1)
It was diluted and introduced. Furthermore, if necessary, trimethylboron (B(CII+)z) is added as a P-type impurity to the system (2
From 3), B(CH:l) s/CHz011 = 0.
By introducing 5 to 3χ, the diamond was made into a P type. Furthermore, S as a dopant.

When adding Se and Te, for example (H2S
or (C113)2S)/C1130H=0.1~
3χ was added. This was mainly added to the upper part of the diamond (the side away from the substrate). Pressure is 0.01~3t
orr was set to, for example, 0.26 torr. A magnetic field of 2.2 KG (kilo Gauss) was applied so that the magnetic field at or near the substrate was 875 Gauss. The microwave adds - to 5, and the thermal energy of this microwave increases the temperature of the substrate by 20.
0 to 1000°C1, for example, 800°C.

Then, the carbon in the alcohol, which is decomposed and turned into plasma by this microwave energy, grows on the substrate, making it possible to grow many columnar single crystal diamonds. At the same time, graphite components are also likely to be formed in addition to this diamond, which reacts with oxygen and hydrogen and re-vaporizes as carbon dioxide or methane gas, resulting in crystallized carbon or diamond (2) as shown in Figure 1 (A). As shown, the film could be grown to an average thickness of 0.5 to 3 μm, for example, an average thickness of 1.3 μm (film formation time: 2 hours).

That is, in FIG. 1, a B-doped diamond layer (2-1), a non-doped, S
, Se or Te-doped diamond l (2-
2) Each diamond (2) is 0.7 μm thick.
, 0.6 μm thick.

Furthermore, as shown in FIG. 1(B), an N-type conductivity type silicon film (3) is formed on the upper side of these by plasma CVD using 300 or more people.
It was formed to a thickness of 0.3 μm. If this formation is performed using a simple plasma CvD device similar to that used for diamond, and the microwave energy is set to below IK-, the temperature of the substrate will be 100 -
Since the temperature is 400'C, a silicon film can be formed. Further, when this is set to 2 to 10 KW, for example, 4 KW, an alloy reaction occurs with the underlying diamond, and silicon carbide can be formed during film formation.

In forming these films, different impurities for P-type and N-type are added, so a multi-chamber system is used to form a diamond film with P-type impurities added, and a diamond film-forming reaction chamber with impurities added to generate a luminescent sensor. It is effective to connect the reaction chamber and the reaction chamber for forming an N-type semiconductor layer to each other for mass production.

In FIG. 1(C), an N-type conductive film was formed, and this was heat-treated to cause the lower junction of silicon to react with the upper part of diamond to form silicon carbide. This silicon carbide film has a structure in which impurities of group 1b and N-type impurities are mixed, and only N-type impurities are added to the silicon.

Next, electrode members (4) and (5) were formed on this upper side by vacuum evaporation or sputtering. This electrode was formed by forming multilayers of transparent ITO (indium tin oxide) and metals such as aluminum, silver, chromium, and molybdenum thereon.

Another method to form this one electrode is to form chromium, react it with silicon to form a CrSi compound (transparent and conductive), and then remove the remaining metallic chromium, Aluminum was formed on this chromium silicon alloy for wire bonding.

Then, a P-type silicon substrate - P-type diamond - N-type silicon or silicon carbide - translucent chromium silicon alloy - aluminum composition is used, and light is emitted to the outside by utilizing the translucency of chromium silicon. I can do it.

In the structure shown in FIG. 1(C), a pair of electrodes, namely a substrate (1), a transparent electrode (4), and an external continuity electrode (5)
A voltage of 10 to 200 V (DC to 100 Hz Dupuis = + ratio 1), for example, 60 V, was applied between the two. After passing an electric current through this diamond, it became possible to emit visible light, especially blue light. The intensity had 16 candela/mt. When only oxygen is added unintentionally at the junction and no sulfur, selenium or tellurium is added, the luminescence intensity is
m”L, or not.

"Example 2" In this example, in Example 1 shown in FIG.
Diamonds were formed with an average thickness of 3 μm, for example 1.2 μm. Thereafter, ultrasonic waves were applied to the diamond surface in an alcoholic liquid mixed with diamond grains to form a damaged layer on the diamond surface and above.

As a result, many recombination centers, such as luminescence centers, were created on the upper surface of this diamond.

Furthermore, N-type silicon carbide was formed thereon to a thickness of 0.1 to 0.5 μm.

Other steps were the same as in Example 1.

Instead of FIG. 2(C), a plurality of electrodes were provided on the upper side, and a voltage of 40 V, for example, was applied between a pair of electrodes. Then, blue light emission with a wavelength of 480 nm could be observed from this point. The intensity was 25 candela/l112, which was even brighter than in Example 1.

"Example 3" In Example 1, only a P-type boron-added layer was used for diamond. Thereafter, group (1) b elements were added to this diamond by ion implantation using an accelerating voltage of 50 to 200 KeV to a concentration of 1×IO+9 to 3×10 “cl”.

Then, this impurity damaged the upper diamond, and it was possible to add the impurity as a luminescent center.

Thereafter, this was annealed in the air, and further N-type silicon carbide was formed thereon. Further, an upper electrode was formed in the same manner as in Example 1.

As a result, in addition to having long-term stability, it emits blue light with a wavelength of 4BOr+Il! , we were able to make it to a strength of over 2Q candela/m2.

``Effect'' Previously, when a voltage of 40V was applied to the substrate for 10 minutes, the temperature of the diamond reached nearly 60°C, causing a reaction between the upper electrode and the diamond, resulting in deterioration.

However, with the structure of the present invention shown above, 6
Even when a pulse voltage of 0 V was applied, visible light emission was achieved, and no decrease in luminance was observed even after continuous application for about one month.

The present invention mainly shows the case where one light emitting element is manufactured.

However, it is effective to fabricate light-emitting devices using a plurality of diamonds on the same substrate, form electrodes, and then scribe and break the diamonds to an appropriate size to form a single or integrated light-emitting device one by one. Furthermore, it is effective to construct a composite integrated electronic device, including such a light emitting device, by integrating a diode, a transistor, a resistor, and a capacitor using the same diamond and using a silicon semiconductor above or below it. be.

[Brief explanation of drawings]

FIG. 1 shows a manufacturing process and a longitudinal cross-sectional view of the diamond light emitting device of the present invention. FIG. 2 shows an example of a magnetic field microwave apparatus for forming diamond according to the present invention. P-type theoretical substrate diamond silicon film translucent electrode electrode for external continuity

Claims (1)

[Claims] 1. A light-emitting device using diamond, characterized in that diamond is provided on a P-type silicon substrate, and N-type silicon carbide or silicon is provided on the diamond. 2. A diamond characterized by comprising the steps of forming diamond on a P-type substrate by plasma vapor deposition, forming N-type silicon carbide or silicon on the diamond, and forming an electrode. A method for manufacturing a light emitting device using 3. A light-emitting device using diamond according to claim 1, characterized in that the diamond has an impurity that becomes a luminescence center or a recombination center inside the diamond.