JPH06224473A - Manufacture of p-n junction containing znse as main ingredient and manufacture of p-n junction device - Google Patents

Abstract

PURPOSE:To manufacture a diode having an excellent crystalline device structure in which p-type, n-type layers have uniform carrier density distributions and a highest efficiency when a blue light emitting diode is manufactured by liquid growth and to obtain a high industrial value. CONSTITUTION:Low resistance p-type layer 1 and n-type layer 2 are formed on a single-crystal substrate 3 containing ZnSe as a main ingredient by an epitaxial growth using a differential-temperature vapor pressure control method with Se as main ingredient of solvent as a p-n junction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a pn junction containing ZnSe as a main component and a method for manufacturing a pn junction device for manufacturing a blue light emitting diode or the like.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional method for forming a pn junction containing ZnSe as a main component. This is first shown in Figure 6.
As shown in (a), high-grade Zn that generally has high resistance
The Se single crystal substrate 11 is made into a low resistance n-type by heat treatment in a Zn solution, and then, as shown in FIG.
On the ZnSe single crystal substrate 11, Se such as Li
The p-type crystal 12 is epitaxially grown by a vapor pressure controlled temperature difference liquid phase epitaxy method using a group a element added as a p-type impurity. In this case, n-type Zn
It is considered that Se is caused by a decrease in Zn vacancy when heat-treated in a Zn solvent, but exhibits n-type conductivity.

[0003]

However, in the subsequent p-type epitaxial growth using a solvent containing Se as a main component, a part of the n-type crystal is subjected to heat treatment with the Se solvent, so that the Se vacancy of that part is lost. The number of particles decreases, the composition changes, and the resistance becomes high. As a result, the device structure is pi
Since the n structure or the pin ^- structure is formed, there is a problem that the electrical characteristics of the device show high resistance.

Further, a p-type bulk single crystal grown by the vapor pressure controlled temperature difference liquid phase epitaxy method using the same Se-based solvent is cleaved in the (110) or (111) orientation, or A method of forming a pn junction by making a part of a p-type crystal n-type by heat-treating a cut-out substrate in a Zn solution at low temperature has been used. However, the n-layer formed by the diffusion method is Carrier density distribution and lattice defects are generated toward the junction surface, it is difficult to control the crystallinity of the n-type diffusion layer, and there are problems in the series resistance and light emission characteristics of the diode.

In either case, p-type crystals are obtained by a method of crystal growth using an Se solvent in which the solubility of ZnSe is larger than Zn at low temperatures, and n-type crystals are obtained by heat treatment using a Zn solution. It is believed that this is due to the method of forming the pn junction by the process of combining the two growth methods.

In view of the above problems, the present invention provides a p-type layer,
The n-type layer has a good crystalline device structure with a uniform carrier density distribution, and the diode with the highest efficiency can be manufactured when a blue light emitting diode or the like is manufactured by liquid phase growth, which has a high industrial value. It is intended to provide a method for manufacturing a pn junction containing ZnSe as a main component and a method for manufacturing a pn junction device.

[0007]

A method for manufacturing a pn junction according to claim 1 is characterized in that a low resistance p-type layer and an n-type layer, and Se as a solvent main component are formed on a single crystal substrate containing ZnSe as a main component. It is characterized in that a pn junction is formed by epitaxial growth using a vapor pressure controlled temperature difference method as a component.

A method for manufacturing a pn junction according to claim 2 is
In addition to the above structure, the growth temperature for the p-type layer is set to 900 as a condition for growing the p-type and n-type layers by epitaxial growth using the vapor pressure controlled temperature difference method using Se as a solvent main component. ˜1100 ° C., the vapor pressure of Zn is in the range of 1.7 to 13.0 atm, the growth temperature is 1000 to 1100 ° C., and the vapor pressure of Zn is 5.0 in the case of an n-type layer.
It is characterized in that it is set to a range of 13.0 atm.

A method for manufacturing a pn junction according to a third aspect is
In addition to the above structure, the p-type layer is added with Na or an Se compound of Na as a p-type impurity as a main component during epitaxial growth using the vapor pressure controlled temperature difference method using Se as a solvent main component. It is characterized by being formed by.

In the pn junction manufacturing method according to the present invention, in addition to the above-mentioned structure, the n-type layer becomes an n-type impurity during epitaxial growth using a vapor pressure controlled temperature difference method using Se as a solvent main component. It is preferably formed by adding Ga, Al, In or a Se compound thereof as a main component. In addition to the above-mentioned structure, the method for manufacturing a pn junction according to the present invention is characterized in that the p-type layer has
The impurity added during the epitaxial growth using the vapor pressure controlled temperature difference method with e as the main component of the solvent is Na ₂ Se.
And about 3 to 8 × 10 ⁻³ mol with respect to the Se solvent.
It is preferably formed by adding in the range of e%. In the pn junction manufacturing method according to the present invention, in addition to the above configuration, it is preferable that the p-type layer and the single crystal substrate containing ZnSe as a main component are removed after the formation of the pn junction. Further, in the method for manufacturing a pn junction according to the present invention, in addition to the above configuration, it is preferable that the single crystal substrate containing ZnSe as a main component is a substrate having a plane orientation of (111) and a high electrical resistance. .

A method of manufacturing a pn junction device according to claim 8 is characterized in that the above-mentioned single crystal substrate containing ZnSe as a main component is epitaxially grown by a vapor pressure controlled temperature difference method using Se as a main component on the single crystal substrate. The n-type layer is epitaxially grown first with the p-type layer first, and then the single crystal substrate containing ZnSe as a main component is removed to leave only the epitaxial growth layer to form a pn junction.

Further, in the method for manufacturing a junction device according to the ninth aspect, the ZnSe is formed by epitaxially growing the p-type layer and the n-type layer by using a vapor pressure controlled temperature difference method using Se as a solvent main component. After the pn junction is formed by sequentially growing it on a single crystal substrate as a main component, a part of the n-type layer and the p-type layer is removed by etching, and ohmic electrodes are formed on each of them. The pn junction is formed without removing the single crystal substrate containing ZnSe as a main component.

[0013]

As described above, the pn junction and the pn junction device containing ZnSe as a main component according to the present invention are unlikely to have the n-type resistance lowered by the increase or decrease of vacancies like the heat treatment method using a Zn solution. And a low carrier resistance and uniform carrier density obtained by epitaxially growing an n-layer on a p-layer or a p-layer on an n-layer using a solvent containing Se as a main component under optimal control of Zn vapor pressure. Of ZnSe formed by the n-type and p-type crystal regions of
It becomes an n-junction and a pn-junction device.

Moreover, ZnSe was originally difficult to obtain a p-type crystal due to the self-compensation effect, and even if it was obtained by any method, only a low carrier density with high resistance was obtained. In liquid phase growth using a solvent containing as a main component, Na or a Se compound of Na is used as a p-type dopant, and thereby a p-crystalline region having low resistance and high carrier density has been successfully obtained.

That is, the pn junction and the pn junction device containing ZnSe as a main component of the present invention are formed by epitaxial growth using a vapor pressure controlled temperature difference method using a solvent containing Se which is the same for both p-type and n-type. Since the structure is such that a pn junction is formed, a part of the p-type crystal is type-inverted by a method such as heat treatment diffusion, or the p-type crystal is grown on the heat-treated low-resistance n-type crystal to form a pn junction. Unlike the case of forming, the p-type and n-type layers each have a uniform carrier density distribution and have a good crystallinity device structure.

[0016]

The present invention will be described in detail below with reference to the illustrated embodiments. FIG. 1 shows Zn produced by the present invention.
It is the schematic of the structure of the pn junction device which has Se as a main component. 1 is Se by adding Na ₂ Se as a p-type impurity.
Is a p-type epitaxial growth layer grown as a solvent main component, and 2 is an n-type epitaxial growth layer grown as a solvent main component by adding, for example, Ga ₂ Se ₃ as an n-type impurity. These epitaxial growth layers 1 and 2
Has a surface grown on a (111) -oriented single crystal substrate, but the substrate crystal must be a single crystal with as few defects as possible and usually has a very high resistance. The structure is such that the original substrate is removed during device formation. In the method of manufacturing a pn junction device containing ZnSe as a main component of the present invention, a diode is manufactured without removing the original substrate by performing selective etching of a growth layer and forming a selective electrode in a device forming process. You may

In the pn junction mainly composed of ZnSe shown in FIG. 1, since the n layer is formed by epitaxial growth from a solvent whose main component is Se, a junction is formed when a p-type layer is formed by a solvent whose main component is Se. Growth of the p-type crystal and n-type crystal with good stoichiometrically controlled crystallinity and uniform carrier density in the growth thickness direction. Layer 1,
A pn-junction device composed of 2 is obtained.
The n-type crystal has a carrier density of 10 ¹⁸ cm ⁻³ and has high carrier and low resistance. The n-type crystal has a carrier density of 10 ¹⁷ c.
Since a crystal having a low resistance can be obtained at m ^-3, it is possible to manufacture a highly efficient light emitting diode or the like.

FIG. 2 shows a procedure for forming a pn junction device containing ZnSe as a main component according to the present invention. Regarding a method for obtaining a bulk ZnSe single crystal for cutting out a growth source substrate, the present inventor has already proposed a vapor pressure control temperature difference method, and a ZnSe liquid phase growth method in which the vapor pressure of Zn is controlled has been proposed. Japanese Patent Publication No. 60-37077, Japanese Patent Publication No. 60-4
No. 2199 and Japanese Patent Publication No. 61-28640. According to these, a p-type or high resistance substrate having excellent crystal perfection can be obtained.

FIG. 2A shows the original substrate 3 for epitaxial growth. The original substrate 3 is cut from a bulk ZnSe single crystal with a diamond saw or the like in the (111) orientation, and then subjected to mechanochemical polishing using brom methanol or aqua regia to completely remove the damage layer caused by cutting and polishing. Use the one removed in. The original substrate 3 may be a substrate cut out from a p-type crystal grown by bulk crystal growth by adding a group Ia element.
From the standpoint of stoichiometric composition, it is preferable to use a high-resistance substrate having higher integrity and no impurities added. Although there are n-type single crystals in low-quality crystals, even if a p-type layer is formed on such a crystal, the p-type layer undergoes transformation to increase the resistance or n
It will be shaped.

First, as shown in FIG. 2B, the original substrate 3
A high carrier p-type layer 1 is epitaxially grown on the upper layer with a thickness of 50 to 100 μm. This epitaxial growth method is also based on the method already disclosed by Japanese Patent Publication No. 60-570759 by the present inventor, but the highest carrier density is obtained as an impurity added to the Se solvent in p-type epitaxial growth. Na ₂ Se is used.

FIG. 3 is a schematic diagram of a p-type crystal Na which is epitaxially grown on a high resistance substrate by a vapor pressure controlled temperature difference method using Na ₂ Se as a p-type crystal growth dopant.
It is a figure which shows the relationship between the addition amount of ₂ Se, and carrier density.
The growth temperature is 900 to 1100 ° C., and the Zn vapor pressure is 1.7 to
It is set within the range of 13.0 atm to control the stoichiometric composition of the grown crystal.

As can be seen from FIG. 3, the carrier density can be controlled from the 10 ¹⁵ cm ^-3 generation depending on the addition amount of Na ₂ Se, but it is 3 to 8 × 10 ^-3 mol with respect to the amount of the Se solvent.
When added in the range of e%, the carrier density of the p-type layer is 1
It is up to 3 × 10 ¹⁸ cm ⁻³ , and a high carrier density is obtained.

Next, as shown in FIG. 2C, Ga ₂ Se as an n-type impurity is formed on the high carrier p-type layer 1.
₃ was added into the Se solvent as in the case of p-type crystals,
Growth temperature 950 to 1100 ° C, Zn vapor pressure 5.0 to 1
Controlled in the range of 3.0 atm, growth thickness 10 to 30 μm
Epitaxial growth is performed to obtain an n-type layer 2 of about m.

Ga at a growth temperature of 1000 ° C. to 1040 ° C.
_{When 2} Se ₃ is added in the range of 1 to 5 × 10 ^-2 mole%, the carrier density of the n-type layer 2 is 0.5 to 2 × 10 ¹⁵ c.
m ^-3 . When the growth temperature is 1060 ° C. to 1100 ° C. and the amount in the same range is added, 0.5 to 6 × 10 ¹⁷ c
An n-type crystal of about m ⁻³ can be obtained. Then, as shown in FIG. 2D, after the growth, the original substrate 3 is removed to remove the p-type crystal, n
A pn junction device containing ZnSe as a main component is realized by leaving only the device growth layers 1 and 2 formed by epitaxial growth of both shaped crystals.

FIG. 4 shows a process for fabricating the device after removing the high resistance substrate 3'after forming the pn junction. FIG. 4A shows that after the p-type layer 1 and the n-type layer 2 are epitaxially grown on the high resistance single crystal substrate 3 ',
The step of leaving the photoresist 4 on the surface of the n-type layer 2 by using an appropriate mask pattern is shown.

FIG. 4B shows a stage in which the n-type layer 2 and a part of the p-type layer 1 are removed by using an etching solution of ZnSe such as aqua regia or bromethanol.

In FIG. 4C, a metal material to be electrodes 5 and 6 is selectively vapor-deposited on the p-type crystal plane exposed by etching and the n-type crystal plane from which the resist 4 is removed, and an inert gas such as Ar gas is used. It shows a stage where an ohmic electrode is formed by performing sintering in a temperature range of 250 ° C to 350 ° C in a gas. Reference numeral 5 is a p-type crystal ohmic electrode made of Au or Au-Zn alloy or the like, and 6 is an n-type crystal ohmic electrode made of Al or the like.

FIG. 4 (d) shows one diode chip cut out along a dotted line A in FIG. 4 (c) with a diamond saw or the like. By manufacturing the device by such a process, the diode can be manufactured without removing the substrate.

According to the above-mentioned embodiment, both the p-type crystal and the n-type crystal are under the optimum Zn pressure control, and both are impurity-added type growth using a solvent containing Se as a main component. There is almost no increase or decrease in the number of vacancies, and the pre-grown p-type crystal or n-type crystal is not metamorphosed or has a high resistance during post-growth. In addition, p-type crystals are also excellent in crystallinity.

FIG. 5 shows the cathode luminescence characteristics of the p-type crystal at 77K at the growth temperature of 950 ° C. and the optimum Zn vapor pressure of 3.0 atm. The exciton emission at 2.773 eV, which is a blue emission transition at room temperature, is the most dominant, and no emission transition at a deep level due to crystal defects, that is, an emission peak on the low energy side is observed at all. The tendency is that the growth temperature is 1100 ° C and the Zn vapor pressure is 1
The same was true when grown at 3.0 atm.

By growing an n-type crystal on the p-type crystal having a good crystallinity, the n-type crystal inherits the good crystallinity of the p-type crystal, and synergizes with the growth under the control of Zn vapor pressure. Due to the effect, a pn junction device having better crystallinity can be realized. Further, since the carrier density of both p-type crystal and n-type crystal can be controlled by the growth temperature and the amount of impurities added, various device structures such as pn, p ⁺ n and p ⁺ n ⁻ can be manufactured.

[0032]

As described above, the ZnSe of the present invention is
The pn junction device containing as a main component uses a solvent having Se as a main component for both p-type and n-type, and a pn junction is formed by epitaxial growth using a vapor pressure controlled temperature difference method. Unlike the case where a part of the p-type crystal is type-inverted by a method such as heat treatment diffusion, or a p-type crystal is grown on an n-type crystal whose resistance has been reduced by heat treatment to form a pn junction. , N-type layers each have a uniform carrier density distribution and a good crystalline device structure can be obtained, which makes it possible to manufacture the most efficient diode when manufacturing a blue light emitting diode or the like by liquid phase growth. It is of high value.

[Brief description of drawings]

FIG. 1 is a diagram showing a pn junction device structure containing ZnSe as a main component of the present invention.

FIG. 2 is a diagram showing a procedure for forming a pn junction device containing ZnSe as a main component of the present invention.

FIG. 3 is a diagram showing the relationship between the amount of p-type dopant added and the carrier density.

FIG. 4 is a diagram showing a process for manufacturing a device after removing a single crystal substrate after forming a pn junction.

FIG. 5 is a diagram showing the cathodoluminescence characteristics of a p-type crystal at 77K.

FIG. 6 is a diagram showing a structure of a conventional pn junction containing ZnSe as a main component.

[Brief description of drawings] [Explanation of symbols]

 1 p-type epitaxial growth layer 2 n-type epitaxial growth layer 3 single-crystal original substrate 3'single-crystal substrate 4 photoresist 5 p-type crystal ohmic electrode 6 n-type crystal ohmic electrode

Claims (9)

[Claims] 1. A low resistance p-type layer and an n-type layer are formed on a single crystal substrate containing ZnSe as a main component by epitaxial growth using a vapor pressure controlled temperature difference method using Se as a solvent main component, Z, characterized by forming a pn junction
A method for manufacturing a pn junction containing nSe as a main component. 2. As a condition for growing the p-type and n-type layers by epitaxial growth using the vapor pressure controlled temperature difference method using Se as a solvent main component, the growth temperature is 900 to The vapor pressure of Zn at 1100 ° C. was 1.
The growth temperature is 1000 to 1100 ° C., and the vapor pressure of Zn is 5.0 to 1 in the case of an n-type layer.
A range of 3.0 atm is set, and the range is set to 1.
7. A method for manufacturing a pn junction containing ZnSe as a main component according to item 1. 3. The p-type layer is formed by adding Na or a Se compound of Na as a p-type impurity as a main component during epitaxial growth using a vapor pressure controlled temperature difference method using Se as a solvent main component. The method for manufacturing a pn junction containing ZnSe as a main component according to claim 1, wherein the pn junction is formed. 4. The n-type layer is Ga, Al, In or their S as an n-type impurity during epitaxial growth using a vapor pressure controlled temperature difference method using Se as a solvent main component.
The method for producing a pn junction containing ZnSe as a main component according to claim 1 or 2, which is formed by adding an e compound as a main component. 5. The impurity added to the p-type layer during epitaxial growth using the vapor pressure controlled temperature difference method using Se as a solvent main component is Na ₂ Se, and the impurity is added to the Se solvent main component. The method for manufacturing a pn junction containing ZnSe as a main component according to claim 1, wherein the pn junction is formed by adding it in a range of approximately 3 to 8 × 10 ^-3 mole%. 6. The ZnSe-based pn according to claim 1, wherein the ZnSe-based single-crystal substrate is removed after the formation of the pn junction. Joining manufacturing method. 7. The single crystal substrate containing ZnSe as a main component is a substrate having a plane orientation of (111) and an electrically high resistance, according to any one of claims 1 to 6. 2. A method for manufacturing a pn junction containing ZnSe as a main component. 8. The Zn is formed by epitaxial growth using a vapor pressure controlled temperature difference method using Se as a solvent main component.
On the single-crystal substrate containing Se as a main component, the p-type layer and the n-type layer were epitaxially grown respectively, and then the single-crystal substrate containing ZnSe as a main component was removed to leave only the epitaxial growth layer. , Pn junction is formed, a method for manufacturing a pn junction device containing ZnSe as a main component. 9. The p-type layer and the n-type layer are sequentially grown on the single crystal substrate containing ZnSe as a main component by epitaxial growth using a vapor pressure controlled temperature difference method using Se as a solvent main component. After forming the pn junction, the n-type layer and a part of the p-type layer are removed by etching, and ohmic electrodes are formed respectively on the n-type layer and the p-type layer to remove the single crystal substrate containing ZnSe as a main component. Without forming a pn junction, Z
A method for manufacturing a pn junction device containing nSe as a main component.