Ammonia for use in manufacture of GaN-type compound...

Details Ammonia for use in manufacture of GaN-type compound... Ammonia for use in manufacture of GaN-type compound...

1999-12-29

2004-04-13

Kunemund, Robert (Department: 1765)

Single-crystal, oriented-crystal, and epitaxy growth processes;

Forming from vapor or gaseous state

With decomposition of a precursor

C117S089000, C117S952000, C423S219000, C423S235000, C423S252000

Reexamination Certificate

active

06719842

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to ammonia for use in the manufacture of a GaN-type compound semiconductor and a method for producing a GaN-type compound semiconductor using the ammonia.
BACKGROUND OF THE INVENTION
FIG. 3
shows an example of conventional GaN-type compound semiconductor devices. The GaN-type compound semiconductor device shown here has a constitution such that a buffer layer
2
comprising Ga
x
Al
1-x
N (wherein 0≦x≦1) which is a GaN-type compound, a Si-doped n-type Ga
x
Al
1-x
N layer (n-type clad layer)
3
which is an n-type clad layer doped with Si, a Zn-doped Ga
x
Al
1-x
N layer (active layer)
4
which is a light emitting active layer doped with Zn, and a Mg-doped p-type Ga
x
Al
1-x
N layer (p-type clad layer)
5
which is a p-type clad layer doped with Mg are laminated in sequence on a sapphire substrate
1
and electrodes
6
and
7
are provided on the n-type clad layer
3
and p-type clad layer
5
, respectively.
This GaN-type compound semiconductor device can be used as a blue light emitting diode.
FIGS. 1 and 2
show an example of a production apparatus for use in the manufacture of the above-described GaN-type compound semiconductor device.
The production apparatus shown here is a metal-organic chemical vapor deposition (MOCVD) reactor and comprises a reaction chamber
11
for housing a sapphire substrate, a support part
12
for holding the sapphire substrate in the reaction chamber
11
, a heater
13
for heating the sapphire substrate supported by the support part
12
, organic metal containers
14
and
15
as supply sources of organic metals, organic metal gas inlet tubes
16
and
17
for introducing organic metal gases supplied from the containers
14
and
15
into the reaction chamber
11
, an ammonia charging container
18
as a supply source of ammonia gas, an ammonia gas inlet tube
19
for introducing the ammonia gas supplied from the charging container
18
into the reaction chamber
11
, an outlet tube
20
for discharging gases out of the reaction chamber
11
, a Si compound container
23
, a Zn compound container
24
, a Mg compound container
25
, and inlet tubes
26
,
27
and
28
for introducing the compounds supplied from the containers
23
,
24
and
25
into the reaction chamber
11
.
The epitaxial wafer for use in the manufacture of the GaN-type compound semiconductor device is manufactured using the above-described production apparatus according to the MOCVD process as described below.
In the production of the GaN-type compound semiconductor device, a sapphire substrate
1
is housed in a reactor
11
, an organic gallium compound housed in a container
14
and an organic aluminum compound housed in a container
15
are bubbled with H
2
gas using tubes
21
and
22
, the organic gallium compound gas and organic aluminum compound gas obtained are introduced together with H
2
gas into the reaction chamber
11
through inlet tubes
16
and
17
, at the same time, ammonia gas supplied from a charging container
18
is introduced into the reaction chamber
11
through an inlet tube
19
, and then a buffer layer
2
comprising Ga
x
Al
1-x
N is formed on the surface of the sapphire substrate 1 using these organic gallium compound gas, organic aluminum gas and ammonia compound gas as raw materials.
Subsequently, a Si compound supplied from a container
23
is fed into the reaction chamber
11
through a tube
26
together with the above-described organic gallium compound, organic aluminum compound and ammonia gas to form an n-type clad layer
3
on the buffer layer
2
.
Then, a Zn compound supplied from a container
24
is fed into the reaction chamber
11
through a tube
27
together with the above-described organic gallium compound, organic aluminum compound and ammonia gas to form an active layer
4
on the n-type clad layer
3
.
Thereafter, a Mg compound supplied from a container
25
is fed into the reaction chamber
11
through a tube
28
together with the above-described organic gallium compound, organic aluminum compound and ammonia gas to form a p-type clad layer
5
on the active layer
4
.
The thus-manufactured epitaxial wafer is removed from the reaction chamber
11
and electrodes
6
and
7
are provided on the n-type and p-type clad layers
3
and
5
, respectively, thereby obtaining a GaN-type compound semiconductor device.
The above-described conventional technique is, however, disadvantageous in that the GaN-type compound semiconductor device obtained tends not to satisfy the light emitting property, particularly brightness. Accordingly, a technique capable of producing a GaN-type compound semiconductor device having excellent light emitting property without failure has been demanded.
SUMMARY OF THE INVENTION
The present invention has been made under these circumstances, and an object of the present invention is to provide a method for manufacturing a GaN-type compound semiconductor, where a GaN-type compound semiconductor having excellent light emitting property can be manufactured without fail.
The present inventors have found that the water concentration in the ammonia gas used as a raw material in the manufacture of GaN-type compound semiconductors has a great effect on the light emitting property such as brightness of the GaN-type compound semiconductor. The present invention has been accomplished based on this finding.
More specifically, the ammonia for use in the manufacture of a GaN-type compound semiconductor of the present invention is filled in a charging container such that at least a part of the ammonia is liquid, and the liquid phase ammonia has a water concentration determined by a Fourier-transform infrared spectroscopy (FT-IR) of 0.5 vol ppm or less.
Furthermore, the method for producing a GaN-type compound semiconductor of the present invention comprises introducing the above-described ammonia in the gaseous state into a reaction chamber housing therein a substrate, and forming a layer comprising a GaN-type compound using the ammonia on the substrate.


REFERENCES:
patent: 3931631 (1976-01-01), Groves et al.
patent: 4001056 (1977-01-01), Groves et al.
patent: 5716588 (1998-02-01), Vergani et al.
patent: 5831277 (1998-11-01), Razeghi
patent: 5834331 (1998-11-01), Razeghi
patent: 0 662 339 (1995-01-01), None
patent: 08-201370 (1996-08-01), None
patent: 09-142833 (1997-06-01), None
patent: 09-251957 (1997-09-01), None
Hiebuhr et al, “Electrical and Optical Properties of Oxygen Doped GaN Grown byMOCVD using N20”, Journal of Electronic Materials, vol 26, No. 10, Oct. 1997.*
Patent Abstract of Japan, JP 09-251957, dated Sep. 22, 1997.

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