JPH05152204A - Iii-v compound semiconductor - Google Patents

Abstract

PURPOSE:To grow a wurtzite type III nitride mixed crystal on a crystal having different crystal structure regarding a wide-gap semiconductor capable of being deposited on a semiconductor substrate. CONSTITUTION:A semiconductor mixed crystal 2 composed of a first component and a second component is deposited on a semiconductor single crystal substrate 1 having zincblende type or diamond type crystal structure. The first component consists of one or two or more of compounds in AlN, GaN and InN, and the second component is made up of one or two or more of compounds in InP, GaP, AlP, InAs, GaAs, AlAs, InSb, GaSb and AlSb. The composition ratio of a first compound to a second compound is represented by a composition, in which the mean interatomic distance of a tetrahedron coordinate bond formed by group V atoms in the crystal structure of the semi-conductor mixed crystal 2 is equalized approximately to the interatomic distance of a tetrahedron coordinate bond formed in the crystal structure of the semiconductor crystal substrate 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a III-V group compound semiconductor in which a wide-gap semiconductor composed of a mixed crystal of a group III nitride semiconductor and a III-V group compound semiconductor is deposited on a substrate.

Group III nitride semiconductors such as InN. G
Since aN, AlN, and mixed crystals of these are wide-gap semiconductors having a band gap exceeding 3 eV, they are regarded as important materials for optical semiconductor devices that can be used in the short wavelength region.

However, in order to widely apply these compound semiconductors as semiconductor element materials, it is necessary to deposit an epitaxial crystal having good crystallinity on the substrate crystal. Therefore, there is a demand for a wide-gap semiconductor that can be deposited in lattice matching on a semiconductor crystal having good crystallinity.

[0004]

2. Description of the Related Art I known as a wide-gap semiconductor
Most group II nitride semiconductors have a wurtzite crystal structure. For this reason, conventionally, epitaxial layers were deposited and manufactured using crystals belonging to the same hexagonal group as substrates.

However, there is no known hexagonal group crystal whose lattice constant matches that of a group III nitride semiconductor and which has few crystal defects. Therefore, conventionally, it has been impossible to manufacture a wide-gap semiconductor crystal with few crystal defects by the epitaxial method.

[0006]

As described above, the conventional
A wide-gap semiconductor made of a group III nitride has a problem that a crystal with few crystal defects cannot be manufactured by an epitaxial growth method because there is no hexagonal substrate crystal with good crystallinity.

The present invention has a wurtzite crystal structure I
A wide-gap III-V compound semiconductor with few crystal defects, which was epitaxially grown using a semiconductor crystal with good crystallinity as a substrate by making the mixed crystal of the group II nitride semiconductor have a composition in which the basic unit of the crystal structure matches the substrate. The purpose is to provide.

[0008]

FIG. 1 is an explanatory view of the principle of the present invention, showing a lattice plane when a wurtzite structure semiconductor mixed crystal grows on a substrate of a sphalerite or diamond structure. 1 (a) shows the one grown on the (111) plane of the substrate, and FIG. 1 (b) shows the one grown on the plane parallel to the <111> direction of the substrate.

The first aspect of the present invention for solving the above problems
The composition is shown in Fig. 1, and the first composition is gemstone type.
And any one of diamond type crystal structure
The first component and the second component deposited on the semiconductor single crystal substrate 1
A semiconductor mixed crystal 2 composed of two components, the first composition
Minute is one or more of AlN, GaN and InN.
It consists of the above compound, and the second component is InP, Ga
P, AlP, InAs, GaAs, AlAs, InS
One or more of b, GaSb and AlSb
The semiconductor mixed crystal 2 and the first component and the second component
In the crystal structure of the semiconductor mixed crystal 2, the ratio of
The average interatomic distance of the tetrahedral coordination bond formed by group atoms is
Interatomic distance of tetrahedral coordination bond in semiconductor crystal substrate 1
The wide gap is characterized by a ratio that is substantially equal to
Configured as a group III-V compound semiconductor, and
The composition is the III-V group compound semiconductor of the first composition,
The semiconductor mixed crystal was deposited on a GaP single crystal ((Al_x
Ga_1-x)_yIn_1-yP)_z(AlN) _1-zAnd x
Is 0 or more and 0.7 or less, and y is 0 or more and 0.5 or less
And z is 0.7 or more and 0.8 or less.
As a direct transition type wide-gap III-V compound semiconductor
Consists of

[0010]

The semiconductor for optical devices according to the present invention is made of AlN, G
It is composed of a mixed crystal containing aN and InN as one component and a III-V group compound semiconductor conventionally used for optical devices as another component.

It is known that the band gap and the lattice constant of the mixed crystal of the III-V group compound semiconductor monotonically change according to the composition ratio. The semiconductor mixed crystal according to the present invention has a large forbidden band width because it contains AlN, GaN, and InN, which have a significantly larger forbidden band width than the commonly used III-V group compound semiconductors. is there.

On the other hand, a semiconductor mixed crystal having an arbitrary lattice constant over a wide range can be manufactured by selecting the kind of the compound as the component of the mixed crystal and the composition ratio thereof.
The present invention selects the composition of the semiconductor mixed crystal containing such a nitride so that the sizes of the basic crystal structures common to the semiconductor mixed crystal and the substrate crystal are substantially the same. The layers can be grown in a lattice-matched manner on substrates with different crystal structures.

That is, the wurtzite crystal structure of the semiconductor mixed crystal has a hexagonal close-packed structure in which the group V atoms form a tetrahedral coordination bond and the tetrahedral coordination structure is a basic structure. In addition, the zinc-blende or diamond-type structure of the substrate has a tetrahedral coordination formed by group V or group IV atoms as the basic structure, which forms a face-centered dense structure.

According to the structure of the present invention, the average size of the tetrahedral coordination structure of the substrate crystal and the semiconductor mixed crystal epitaxially grown thereon, that is, the average interatomic distance of the tetrahedral coordination, is substantially the same. The composition of the semiconductor mixed crystal is selected.

In such a structure, the difference in crystal structure can be absorbed at the interface between the substrate crystal and the epitaxial semiconductor mixed crystal without generating a crystal defect such as a dislocation which propagates into the epitaxial layer, as described below. it can.

As is well known, referring to FIG. 1, a gemstone or diamond type structure has three lattice planes A, B and C in which the above-mentioned tetrahedral coordination structure is displaced in-plane. The wurtzite structure has a hexagonal close-packed structure in which two lattice planes A and B are alternately stacked.

In the present invention, since the tetrahedral coordination sizes are substantially the same, the lattice planes of the substrate and the semiconductor mixed crystal are regarded as the same plane in terms of crystal structure. That is, in epitaxial growth having an interface on the (111) plane, as shown in FIG.
ABCABC and three lattice planes are sequentially laminated on the surface of the substrate on which the A and B planes are alternately laminated with AB. As described above, since the lattice planes of the substrate and the semiconductor mixed crystal are the same, no lattice irregularity such as dislocation that propagates in the epitaxial layer occurs between the substrate and the semiconductor mixed crystal.

When a growth surface other than the (111) plane, for example, a plane parallel to <111> is used as the growth surface,
Referring to (b), a matching lattice plane 3a where the crystal lattice is matched and an unmatched lattice plane 3b where the crystal lattice is mismatched at the interface between the substrate and the semiconductor mixed crystal. This mismatched lattice plane causes 60 ° half dislocations and stacking faults at the interface with the substrate. However, these lattice irregularities remain at the interface between the substrate and the epitaxial layer and do not propagate into the epitaxial layer.

As described above, in the present invention, the composition is such that the average interatomic distance of tetrahedral coordination is substantially equal to the interatomic distance of the substrate crystal, so that the half dislocations and stacking faults are separated from the substrate and the semiconductor mixed crystal. In addition to occurring at the interface, there are no defects that propagate in the epitaxial layer, so a semiconductor mixed crystal with good crystallinity is deposited.

The semiconductor mixed crystal according to the second structure of the present invention is
This is a mixed crystal of a semiconductor in which the composition ratio of Al, Ga, In, and P is in the range of direct transition type, and AlN of direct transition type as well, and has a direct transition type energy band structure. Therefore, it is an excellent material for highly efficient light emitting and light receiving elements.

Further, in this structure, GaP is used for the substrate,
The component other than AlN is a P compound. Therefore, it is possible to prevent the deterioration of crystallinity due to the redistribution of group V atoms on the substrate surface during epitaxial growth.

The mismatch of the interatomic distance between the substrate and the epitaxial layer is usually preferably 1% or less in order to avoid the occurrence of mismatch dislocation. In addition, the composition ratio of In can be a composition confirmed to be a direct transition type in (Al _x Ga _1-x ) _y In _1-y P.
Such a composition is realized when y is 0 or more and 0.5 or less and z is 0.7 or more and 0.8 or less.

[0023]

EXAMPLES Details of the present invention will be described with reference to examples.
In the first embodiment of the present invention, a GaP single crystal is used as a substrate ((A
l_xGa_1-x)_yIn _1-yP)_z(AlN)_1-zDeposited
To do.

The interatomic distance of tetrahedral coordination of the compound as each component of this example is 0.1917 nm for AlN and 0.2367 for AlP.
nm, GaP is 0.2358 nm, and InP is 0.254 nm. Therefore, the average interatomic distance d can be obtained by using Vegard's law as d = 0.1917 (1-z) + ((0.2367x + 0.2358 (1-x)) y + 0.254 (1-y)) z. Where (Al _x Ga _1-x ) yIn
_{If 1-y} P is a direct transition type x = 0.7, y = 0.5, and d is equal to the GaP interatomic distance of 0.2358 nm, z =
It becomes 0.8. A semiconductor mixed crystal of this composition is a direct transition type, and its band gap is about 2.9 eV.

A semiconductor mixed crystal having such a composition ratio of the present embodiment is I
It can be deposited on an nP substrate to form a light emitting layer of a blue light emitting diode. It can also be applied to the cladding layer of a light emitting device by utilizing a large forbidden band width. further,
According to this embodiment, since the substrate capable of emitting green light and the epitaxial layer emitting blue light can be stacked and deposited, it is easy to realize the emission of the three primary colors.

The III-V group compound semiconductor of this embodiment is deposited by a method usually used in the epitaxial growth of compound semiconductors, for example, a CVD method using ammonia, or MB.
Method E can be used.

The second embodiment of this embodiment uses a GaP single crystal as a substrate to deposit (AlAs) _1-z (AlN) _z . As in the first embodiment, the interatomic distance d in the tetrahedral coordination of the semiconductor mixed crystal is d = 0.2451 (1-z) + 0.1917z. Here, the interatomic distance of tetrahedral coordination of AlAs, 0.
2451 nm was used. If d is set equal to the interatomic distance of GaP, we obtain z = 0.2. The semiconductor mixed crystal having this composition has a particularly large band gap.

[0028]

According to the present invention, a wurtzite-type semiconductor single crystal can be epitaxially grown on a zinc-zinc-type or diamond-type semiconductor substrate crystal with matching lattice planes, so that the crystallinity is good. A wide-gap III-V group compound semiconductor that can be deposited on a semiconductor substrate and has few crystal defects can be formed by using a semiconductor crystal as a substrate to deposit a mixed crystal containing a group III nitride having a large forbidden band. Can contribute to improving the performance of optical semiconductor devices.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the present invention.

[Explanation of symbols]

 1 substrate 2 semiconductor mixed crystal 3 lattice plane 3a matching lattice plane 3b unmatched lattice plane

Claims (2)

[Claims] 1. A semiconductor single crystal substrate (1) having a crystal structure of any one of a sphalerite type and a diamond type.
A semiconductor mixed crystal (2) deposited on the first component and the second component, wherein the first component is one or more compounds of AlN, GaN and InN. And the second component is InP, GaP, AlP, InAs,
GaAs, AlAs, InSb, GaSb and AlSb
Of the semiconductor mixed crystal (2), the ratio of the first component to the second component of the semiconductor mixed crystal (2) is V group in the crystal structure of the semiconductor mixed crystal (2). A wide gap characterized in that the average interatomic distance of tetrahedral coordination bonds formed by atoms is in a ratio substantially equal to the interatomic distance of tetrahedral coordination bonds in the semiconductor crystal substrate (1).
Group III-V compound semiconductors. 2. The III-V group compound semiconductor according to claim 1, wherein the semiconductor mixed crystal is deposited on a GaP single crystal ((Al _x
Ga _1-x ) _y In _1-y P) _z (AlN) _1-z , x is 0 or more and 0.7 or less, y is 0 or more and 0.5 or less, and z is 0.7 or more. A direct transition type wide-gap III-V group compound semiconductor characterized by being 0.8 or less.