U.S. patent application number 13/513217 was filed with the patent office on 2012-12-13 for method for producing hydrogenated polygermasilane and hydrogenated polygermasilane.
This patent application is currently assigned to SPAWNT PRIVATE S.A.R.L.. Invention is credited to Norbert Auner, Christian Bauch, Rumen Deltschew, Thoralf Gebel, Sven Holl, Gerd Lippold, Javad Mohsseni.
Application Number | 20120315392 13/513217 |
Document ID | / |
Family ID | 43499339 |
Filed Date | 2012-12-13 |
United States Patent
Application |
20120315392 |
Kind Code |
A1 |
Auner; Norbert ; et
al. |
December 13, 2012 |
METHOD FOR PRODUCING HYDROGENATED POLYGERMASILANE AND HYDROGENATED
POLYGERMASILANE
Abstract
A process for preparing hydrogenated polygermasilane as a pure
compound or mixture of compounds includes hydrogenating halogenated
polygermasilane.
Inventors: |
Auner; Norbert;
(Glashuetten, DE) ; Bauch; Christian;
(Muldenstein, DE) ; Holl; Sven; (Gueckingen,
DE) ; Deltschew; Rumen; (Leipzig, DE) ;
Mohsseni; Javad; (Bitterfeld-Wolfen, DE) ; Lippold;
Gerd; (Leipzig, DE) ; Gebel; Thoralf;
(Dresden, DE) |
Assignee: |
SPAWNT PRIVATE S.A.R.L.
Luxembourg
LU
|
Family ID: |
43499339 |
Appl. No.: |
13/513217 |
Filed: |
December 6, 2010 |
PCT Filed: |
December 6, 2010 |
PCT NO: |
PCT/EP2010/068994 |
371 Date: |
August 30, 2012 |
Current U.S.
Class: |
427/226 ;
106/286.4; 423/324 |
Current CPC
Class: |
C08G 77/60 20130101;
Y02P 20/582 20151101; C08G 79/14 20130101; C01G 17/00 20130101;
C01B 33/04 20130101 |
Class at
Publication: |
427/226 ;
423/324; 106/286.4 |
International
Class: |
C01B 33/00 20060101
C01B033/00; B05D 3/02 20060101 B05D003/02; C09D 1/00 20060101
C09D001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 4, 2009 |
DE |
10 2009 056 731.3 |
Claims
1. A process for preparing hydrogenated polygermasilane as a pure
compound or mixture of compounds comprising hydrogenating
halogenated polygermasilane.
2. The process according to claim 1, where the halogenated
polygermasilane is selected from the group consisting of thermally
prepared halogenated polygermasilane and plasma-chemically prepared
halogenated polygermasilane.
3. The process according to claim 1, where the halogenated
polygermasilane is reacted with at least one hydridic hydrogenating
agent selected from the group consisting of metal hydrides and
metalloid hydrides.
4. The process according to claim 3, where the hydrogenating agents
is at least one selected from the group consisting of MH,
MBH.sub.4, MBH.sub.4-xR.sub.x, MAlH.sub.4 and
AlH.sub.xR.sub.3-x.
5. The process according to claim 1, where hydrogenation is carried
out at a temperature of -60.degree. C. to 200.degree. C.
6. The process according to claim 1, where hydrogenation is carried
out at a pressure of 1 Pa to 2000 hPa.
7. The process according to claim 1, where the halogenated
polygermasilane is diluted in a solvent prior to hydrogenation.
8. A hydrogenated polygermasilane as a pure compound or mixture of
compounds comprising: substituents Z comprising hydrogen, a ratio
of Z to germanium/silicon of at least 1:1, an averaged formula
Si.sub.aGe.sub.bZ.sub.z, where a+b=1 and z is 1.ltoreq.z.ltoreq.3,
and an average chain length n with 2.ltoreq.n.ltoreq.100.
9. The hydrogenated polygermasilane according to claim 8, prepared
by a process according to claim 1.
10. The hydrogenated polygermasilane according to claim 8, which
has at least 0.0001 mol % of direct bonds between a germanium atom
and a silicon atom.
11. The hydrogenated polygermasilane according to claim 8, having a
fraction of polygermasilane molecules having more than three
directly connected germanium atoms and/or silicon atoms, where at
least 8% of these germanium atoms and/or silicon atoms are
branching sites.
12. The hydrogenated polygermasilane according to claim 8, which is
a mixture of compounds where the mixture has a higher solubility
than at least one individual compound present in the mixture.
13. The hydrogenated polygermasilane according to claim 8, having a
fraction of polygermasilane molecules having more than three
directly connected germanium atoms and/or silicon atoms where the
polygermasilane molecules have an averaged formula
Si.sub.aGe.sub.bZ.sub.z where a+b=1 and
1.9.ltoreq.z.ltoreq.2.5.
14. The hydrogenated polygermasilane according to claim 8, where Z
additionally comprises halogen.
15. The hydrogenated polygermasilane according to claim 14, where a
fraction of halogen is less than 2 atom %.
16. The hydrogenated polygermasilane according to claim 8, where a
fraction of hydrogen is greater than 50 atom %.
17. The hydrogenated polygermasilane according to claim 8, which in
.sup.1H NMR spectra has significant product signals in the chemical
shift range of 6.1 to 2.0 ppm.
18. The hydrogenated polygermasilane according to claim 8, which in
.sup.1H NMR spectra has at least 80% of signal intensity of a total
integral of its significant product signals in a chemical shift
range of 5.0 to 2.9 ppm.
19. The hydrogenated polygermasilane according to claim 8, which in
.sup.29Si NMR spectra has significant product signals in a chemical
shift range of -80 to -130 ppm.
20. The hydrogenated polygermane according to claim 8, which in
Raman spectra has significant product bands of 2250 to 2000
wavenumbers and at below 550 wavenumbers.
21. The hydrogenated polygermasilane according to claim 8, which is
colorless to yellow or ivory.
22. The hydrogenated polygermasilane according to claim 8, which is
an amorphous or a crystalline solid.
23. The hydrogenated polygermasilane according to claim 8, which is
soluble at least to an extent of 20% at concentrations of up to 10%
in inert solvents.
24. The hydrogenated polygermasilane according to claim 23, where
readily soluble hydrogenated polygermasilane is distillable and/or
volatile without decomposition to an extent of more than 20% under
reduced pressure.
25. A silicon-germanium layer produced from a hydrogenated
polygermasilane according to claim 8.
26. A method for producing a silicon-germanium layer on a substrate
comprising: A) applying a solid or dissolved hydrogenated
polygermasilane according to claim 8 to a substrate; and B)
pyrolyzing the hydrogenated polygermasilane.
Description
RELATED APPLICATIONS
[0001] This is a .sctn.371 of International Application No.
PCT/EP2010/068994, with an international filing date of Dec. 6,
2010 (WO 2011/067417 A1, published Jun. 9, 2011), which is based on
German Patent Application No. 10 2009 056 731.3, filed Dec. 4,
2009, the subject matter of which is incorporated by reference.
TECHNICAL FIELD
[0002] This disclosure relates to a process for preparing
hydrogenated polygermasilane, and also hydrogenated polygermasilane
as a pure compound or mixture of compounds.
BACKGROUND
[0003] Known processes for preparing polygermasilane are carried
out with GeH.sub.4 and short-chain silanes as starting materials,
with the consequences first that it is necessary to deal with
substances hazardous to health and difficult to handle, that only
certain polygermasilanes are accessible, usually multistage
syntheses are required, and in these syntheses the yields obtained,
especially of long-chain polygermasilanes, are often low. In
particular, it has to date not been possible to prepare
longer-chain compounds in a targeted way.
[0004] Polygermasilanes are disclosed in U.S. 2007/0078252 A1, for
example.
[0005] It could be helpful to provide a simplified process for
preparing hydrogenated polygermasilane that exhibits an improved
yield relative to known processes, and also to provide hydrogenated
polygermasilane having improved properties.
SUMMARY
[0006] We provide a process for preparing hydrogenated
polygermasilane as a pure compound or mixture of compounds
including hydrogenating halogenated polygermasilane.
[0007] We also provide a hydrogenated polygermasilane as a pure
compound or mixture of compounds including substituents z including
hydrogen, a ratio of z to germanium/silicon of at least 1:1, an
averaged formula Si.sub.aGe.sub.bZ.sub.z, where a+b=1 and z is
1.ltoreq.z.ltoreq.3, and an average chain length n with
2.ltoreq.n.ltoreq.100.
[0008] We further provide a silicon-germanium layer produced from
the hydrogenated polygermasilane.
[0009] We still further provide a method for producing a
silicon-germanium layer on a substrate including A) applying a
solid or dissolved hydrogenated polygermasilane to a substrate, and
B) pyrolyzing the hydrogenated polygermasilane.
DETAILED DESCRIPTION
[0010] We provide a process for preparing hydrogenated
polygermasilane as a pure compound or mixture of compounds, where
halogenated polygermasilane is hydrogenated. Hydrogenated
polygermasilane may mean, for example, a pure compound or a mixture
of compounds which in each case have at least one direct bond
between two germanium atoms and/or between two silicon atoms and/or
between one germanium atom and one silicon atom.
[0011] The hydrogenated polygermasilane may have substituents Z
comprising hydrogen, a ratio of Z to germanium/silicon of at least
1:1, an averaged formula Si.sub.aGe.sub.bZ.sub.z, where a+b=1 and z
is selected from 1.ltoreq.z.ltoreq.3, preferably
1.5.ltoreq.z.ltoreq.3, more preferably 2.ltoreq.z.ltoreq.3, and an
average chain length n with 2.ltoreq.n.ltoreq.100.
[0012] The term "pure compound" is understood below to mean that
the hydrogenated polygermasilane comprises compounds having no
differences in their chain length, if present in their branches
and/or in the number and nature of their rings. In other words,
only one fraction of hydrogenated polygermasilane is present in a
pure compound. "Pure" here is to be understood in accordance with
typical fine-chemicals yardsticks. Accordingly, even pure compounds
may include small fractions of impurities, examples being traces of
carbon or halogens, or small fractions of different hydrogenated
polygermasilanes. Small fractions in this context are less than 0.5
mol %, preferably less than 10 ppm.
[0013] Analogously, "mixture of compounds" is understood below to
mean that the hydrogenated polygermasilane has at least two
fractions whose hydrogenated polygermasilanes differ in their chain
length, if present in their branches and/or in their nature and
number of rings.
[0014] Accordingly, either all of the molecules of the pure
compound or all of the molecules of the at least two fractions of
the mixture of compounds may in each case have at least one direct
bond between two germanium atoms and/or between two silicon atoms
and/or between one germanium atom and one silicon atom.
[0015] We accordingly provide a process for preparing hydrogenated
polygermasilane with which for longer-chain polygermasilanes in
particular, the yields are increased relative to known preparation
processes, and any desired chain lengths are rendered accessible.
By virtue of the fact that hydrogenated polygermasilane is prepared
from halogenated polygermasilane, the structure present in the
halogenated polygermasilane may also be largely retained in the
hydrogenated polygermasilane or may be coincident with that
structure.
[0016] "Largely" in this case means at least 50%. During
hydrogenation, however, there may also be rearrangements of the
existing structure of the halogenated polygermasilane resulting,
for example, in more branches in the hydrogenated polygermasilane
than were present in the starting material, the halogenated
polygermasilane. However, according to the halogenated
polygermasilane from which they are prepared, the hydrogenated
polygermasilanes prepared by the process may remain
distinguishable.
[0017] With the process it is possible to prepare pure compounds or
mixtures of compounds of fully hydrogenated polygermasilanes which
have Formula Ge.sub.xSi.sub.yH.sub.z with x+y.gtoreq.2,
x+y.gtoreq.z.gtoreq.2(x+y)+2. Preparation takes place by
hydrogenation of halogenated polygermasilanes of Formula
Ge.sub.xSi.sub.yX.sub.z with x+y.gtoreq.2, X=F, Cl, Br, I or
mixtures thereof, x+y.gtoreq.z.gtoreq.2(x+y)+2.
[0018] It is possible with this process to prepare hydrogenated
polygermasilanes and also hydrogenated oligogermasilanes.
Hydrogenated oligogermasilanes have a chain length n=x+y which is
selected from the range 2.gtoreq.n.gtoreq.8. Their empirical
formula is Ge.sub.xSi.sub.yZ.sub.z with x+y.gtoreq.2,
x+y.ltoreq.z.ltoreq.2(x+y)+2. Hydrogenated polygermasilanes have
chain length n=x+y of n>8 and an empirical formula for the
mixture of Ge.sub.xSi.sub.yZ.sub.z. In principle, chain lengths of
2.ltoreq.n.ltoreq.6 are referred to as short-chain, and chain
lengths of n>6 as long-chain. By "chain length" is meant the
number of silicon atoms and/or germanium atoms joined to one
another directly.
[0019] The halogenated polygermasilane may be selected from
thermally prepared halogenated polygermasilane and
plasma-chemically prepared halogenated polygermasilane. Thermally
prepared halogenated polygermasilane may have a higher fraction of
branches than plasma-chemically prepared halogenated
polygermasilane, which may be largely free from branches. The
halogenated polygermasilanes may be pure compounds or mixtures of
compounds.
[0020] A process for preparing plasma-chemically prepared
halogenated polygermasilane is disclosed in WO 2010/031390, for
example, the subject matter of which is incorporated herein by
reference.
[0021] The halogenated, more particularly highly halogenated,
polygermasilanes may have substituents selected from a group
encompassing F, Cl, Br, and I, and mixtures thereof. During
hydrogenation, these halogens may be replaced largely completely by
H as a substituent. Largely completely here means at least an
extent of 50%. The halogen content of the hydrogenated
polygermasilane which is prepared by this process may be less than
2 atom %, more particularly less than 1 atom %. A hydrogenated
polygermasilane may therefore have exclusively hydrogen, or
hydrogen and a halogen, chlorine, for example, as substituents
Z.
[0022] The chlorine content of a compound or a mixture, i.e., both
of chlorinated polygermasilane and a hydrogenated polygermasilane
prepared therefrom, is determined by complete digestion of the
sample and subsequent titration of the chloride by the method of
Mohr. The H content is determined by integration of .sup.1H NMR
spectra, using an internal standard, and comparison of the
resultant integrals, where the mixing ratio is known. The molar
masses of the halogenated and hydrogenated polygermasilanes, and
the average molar mass of the halogenated and hydrogenated
polygermasilane mixtures, are determined by freezing-point
depression. From the stated variables it is possible to determine
the ratio of halogen and/or hydrogen to silicon/germanium.
[0023] The halogenated polygermasilane can be reacted with hydridic
hydrogenating agents selected from metal hydrides and/or metalloid
hydrides. Metal hydrides and/or metalloid hydrides also comprehend
mixed metal hydrides and/or metalloid hydrides respectively, in
other words hydrides which contain different metals and/or
metalloids or a metal and an organic radical. The hydrogenating
agents may be selected from a group encompassing MH, MBH.sub.4,
MBH.sub.4-xR.sub.x, MAlH.sub.4, AlH.sub.xR.sub.3-x, and suitable
mixtures thereof. Examples of such agents are LiAlH.sub.4, DibAlH
(diisobutyl=Dib), LiH, and HCl. Preference is given to mild
hydrogenating agents which permit hydrogenation of halogenated
polygermane without alteration of the germane-silicon backbone.
[0024] Hydrogenation may be carried out at a temperature
encompassing -60.degree. C. to 200.degree. C. The temperature range
may preferably be -30.degree. C. to 40.degree. C., more
particularly -10.degree. C. to 25.degree. C. Furthermore,
hydrogenation may be carried out at a pressure selected
encompassing 1 Pa to 2000 hPa, preferably 1 hPa to 1500 hPa, more
preferably 20 hPa to 1200 hPa. Accordingly, gentle hydrogenation
conditions are set up with pressures and temperatures lower in
comparison to the prior art. In this way, even less-stable
halogenated polygermasilanes can be hydrogenated with a good yield
and a high conversion rate.
[0025] The halogenated polygermasilane can be diluted in a solvent
prior to hydrogenation. The solvent in this case is selected such
that it is inert toward the halogenated polygermasilane--that is,
does not enter into any chemical reaction with it. Inert solvents
selected may be alkanes or aromatics, examples being benzene,
toluene or hexane. Mixtures of solvents are conceivable as well.
Hydrogenation may alternatively be carried out with undissolved
halogenated polygermasilane as well.
[0026] With this process, therefore, hydrogenated polygermasilane
can be prepared in a good yield, in any desired chain length, and
with precursors that present little hazard. Moreover, by a suitable
selection of the precursors, it is possible largely to dictate the
structure of the hydrogenated polygermasilane. Furthermore, a
largely complete hydrogenation of the halogenated polygermasilane
can be achieved with this process.
[0027] Additionally specified is a hydrogenated polygermasilane as
a pure compound or mixture of compounds. The hydrogenated
polygermasilane has substituents Z comprising hydrogen, a ratio of
Z to germanium/silicon of at least 1:1, an averaged formula
Si.sub.aGe.sub.bZ.sub.z, where a+b=1 and z is selected from
1.ltoreq.z.ltoreq.3, preferably 1.5.ltoreq.z.ltoreq.3, more
preferably 2.ltoreq.z.ltoreq.3, and an average chain length n with
2.ltoreq.n.ltoreq.100. A hydrogenated polygermasilane may be, for
example, a pure compound or a mixture of compounds which in each
case have at least one direct bond between two germanium atoms
and/or between two silicon atoms and/or between one germanium atom
and one silicon atom.
[0028] With regard to the terms "pure compound" and "mixture of
compounds," the statements already made in connection with the
process apply analogously. It is the case in turn that "pure" is
understood under typical fine-chemicals yardsticks. Accordingly,
even pure compounds may include small fractions of impurities,
examples being traces of carbon or halogens. Small fractions here
are less than 0.5 mol %, preferably less than 10 ppm.
[0029] "Chain length" means the number of silicon atoms and/or
germanium atoms attached to one another directly. The chain length
of the hydrogenated polygermasilane may be selected more
particularly from 4.ltoreq.n.ltoreq.50, more particularly from
6.ltoreq.n.ltoreq.20.
[0030] The averaged formula Ge.sub.aSi.sub.bZ.sub.z is to be
understood, accordingly, to mean that a germanium atom or a silicon
atom in the hydrogenated polygermasilane has on average 1 to 3
substituents Z. Taken into account here are the germanium atoms and
silicon atoms both in linear polygermasilanes and also in rings or
branched polygermasilanes. A hydrogenated polygermasilane of this
kind is suitable for a multiplicity of applications on the basis of
its chemical properties.
[0031] The hydrogenated polygermasilane may have been prepared by a
process according to the statements above. Accordingly it is
prepared by hydrogenation of halogenated polygermasilanes. Through
the preparation process, therefore, the structure of the
hydrogenated polygermasilane may be derivable from the structure of
the halogenated polygermasilane or may be coincident with it.
[0032] For example, largely linear hydrogenated polygermasilanes
may be obtained by hydrogenating plasma-chemically prepared
halogenated polygermasilanes or hydrogenated polygermasilanes
having a high fraction of branches may be obtained by hydrogenating
thermally prepared halogenated polygermasilanes. Hydrogenation may
be carried out largely completely, and so the substituents Z in the
polygermasilane largely comprise hydrogen. "Largely" here means
again a fraction of hydrogen among the substituents of at least
50%. The hydrogenation, however, may also proceed to completion,
giving a 100% fraction of hydrogen as substituent Z.
[0033] The hydrogenated polygermasilane may have at least 0.0001
mol % of direct bonds between a germanium atom and a silicon atom.
Present accordingly is not only a mixture of polygermanes and
polysilanes, but rather compounds in pure form and in the form of a
mixture that contains both germanium and silicon in their
chains.
[0034] The hydrogenated polygermasilane may have a fraction of
polygermasilane molecules having more than three directly connected
germanium atoms and/or silicon atoms, where at least 8%, more
particularly more than 11%, of these germanium atoms and silicon
atoms are branching sites. The fraction of polygermasilane
molecules having more than three directly connected germanium atoms
and/or silicon atoms in this case may be a pure compound, or may be
a fraction of the hydrogenated polygermasilane in the case of a
mixture of compounds. In each case, such polygermasilane molecules
have a chain length of n>3. The term "branching sites" refers
both to germanium atoms and silicon atoms connected to more than
two other germanium atoms and/or silicon atoms, in other words
having only one substituent Z or none at all. Branching sites may
be determined by .sup.1H NMR spectra, for example.
[0035] The hydrogenated polygermasilane which is a mixture of
compounds may in the form of the mixture have a higher solubility
than at least one individual compound present in the mixture.
Hence, at least one individual component of the mixture has a lower
solubility than the individual component in conjunction with the
other components of the mixture of compounds. The reason that lies
behind this is that the different components of the mixture act
mutually as solubilizers. In principle, shorter-chain molecules
have a better solubility than their longer counterparts, and so in
a mixture of compounds they also improve the solubility of the
longer-chain molecules.
[0036] The hydrogenated polygermasilane may have a fraction of
polygermasilane molecules having more than three directly connected
germanium atoms and/or silicon atoms, where these polygermasilane
molecules have an averaged formula Si.sub.aGe.sub.bZ.sub.z where
a+b=1 and 1.9.ltoreq.z.ltoreq.2.5. More particularly, z may be
selected from 2.0.ltoreq.z.ltoreq.2.4.
[0037] Furthermore, the hydrogenated polygermasilane may have a
substituent Z which additionally comprises a halogen. Accordingly,
as well as hydrogen, the hydrogenated polygermasilane may also have
halogens, examples being F, Br, I or Cl, or mixtures thereof, as
substituents. In this case, the fraction of halogen in the
hydrogenated polygermasilane may be less than 2 atom %, more
particularly less than 1 atom %. We accordingly provide a largely
hydrogenated polygermasilane which has only a low fraction of
halogen substituents.
[0038] Furthermore, the hydrogenated polygermasilane may have a
fraction of hydrogen which is greater than 50 atom %, preferably
greater than 60 atom %, more particularly greater than 66 atom %.
The hydrogenated polygermasilane thus has a very high fraction of
hydrogen, whereby the ratio of substituent to silicon/germanium of
at least 1:1 is established in conjunction with a high hydrogen
content.
[0039] In .sup.1H NMR spectra, the hydrogenated polygermasilane may
have significant product signals in the chemical shift range of 6.1
to 2.0 ppm, more particularly 5 to 2.1 ppm. "Significant" in this
context means that an integral is greater than 1% of the total
integral. Furthermore, in .sup.1H NMR spectra, the hydrogenated
polygermasilane may have at least 80% of the signal intensity of
the total integral of its significant product signals in the
chemical shift range of 5.0 to 2.9 ppm, more particularly 4.0 to
3.0.
[0040] In .sup.29Si NMR spectra, the hydrogenated polygermasilane
may have significant product signals in the chemical shift range of
-80 to -130 ppm.
[0041] Furthermore, in Raman spectra, the hydrogenated polygermane
may have significant product bands of 2250 to 2000 wavenumbers and
at below 550 wavenumbers. "Significant" in connection with Raman
spectra means more than 10% of the intensity of the highest
peak.
[0042] The hydrogenated polygermasilane may be colorless to yellow
or ivory. It may be present as an amorphous or crystalline solid.
It is preferably not of high viscosity.
[0043] Furthermore, the hydrogenated polygermasilane may be soluble
at least to an extent of 20% at concentrations of up to 10% in
inert solvents. This means that at least one compound of a mixture
of compounds of the hydrogenated polygermasilane is readily soluble
in inert solvents. Inert solvents are those solvents which do not
react with the hydrogenated polygermasilane. It is possible, for
example, to select solvents selected from a group encompassing
benzene, toluene, cyclohexane, SiCl.sub.4, and GeCl.sub.4.
[0044] The readily soluble hydrogenated polygermasilane of the
aforementioned mixture of compounds may be distillable and/or
volatile without decomposition to an extent of more than 20%,
preferably to an extent of more than 80%, under reduced pressure.
The reduced pressure in this case comprises preferably 1 to 100 Pa.
Accordingly, the hydrogenated polygermasilane can be isolated
effectively.
[0045] We additionally provide a silicon-germanium layer produced
from a hydrogenated polygermasilane according to the statements
above.
[0046] The hydrogenated polygermasilane, then, is a starting
compound readily available on an industrial scale for production of
silicon-germanium layers. As a result of the low pyrolysis
temperature of less than 500.degree. C., preferably less than
450.degree. C., the hydrogenated polygermasilane is a single-source
precursor with which it is possible, at a low temperature, to
deposit silicon-germanium alloys in the form of layers on
substrates. The low pyrolysis temperature permits a relatively
large selection of materials for the carrier layers and substrates
to which silicon-germanium layers are applied, examples being
carrier layers of glass. Moreover, diffusion of impurities from the
carrier material into the resultant silicon-germanium layer will be
diminished or avoided.
[0047] Silicon-germanium layers of this kind can be used, for
example, in photovoltaics or in the electronics industry.
Additionally possible are applications in organometallic chemistry
as, for example, for the production of conductive polymers or
light-emitting diodes.
[0048] A method for producing a silicon-germanium layer on a
substrate comprises the method steps of A) applying a solid or
dissolved hydrogenated polygermasilane according to the statements
above to a substrate and B) pyrolyzing the hydrogenated
polygermasilane. This method leads, with high yields and high
conversion rates, to silicon-germanium layers produced from
hydrogenated polygermasilanes. The hydrogenated polygermasilanes
can be processed with a higher yield and a higher conversion rate
than conventional mixtures of silicon and germanium precursors, to
form silicon-germanium layers. In this context, dissolved or else
solid hydrogenated polygermasilanes can be applied in an easy way
to the substrate. CVD (chemical gas-phase deposition), PVD
(physical gas-phase deposition) or plasma deposition is therefore
not necessary. Provided, therefore, is a simplified method for
producing silicon-germanium layers.
[0049] Indicated below is a working example that relates to
preparation of a hydrogenated polygermasilane.
[0050] A polychlorogermasilane (PCGS) generated by plasma reaction
of GeCl.sub.4 with SiCl.sub.4 and H.sub.2 takes the form of a
highly viscous oil or a solid, each with a color of yellow to
orange-brown. 8.5 g (60 mmol GeCl.sub.2 equivalents) of the PCGS
are admixed with 40 ml of absolute benzene and undergo partial
dissolution as a result. At 0.degree. C., 26 ml of
diisobutylaluminum hydride (145 mmol, about 20% excess) are added
dropwise over the course of 30 minutes. Over the course of about 1
hour, the orange sediment reacts to form a pale yellow powder. The
reaction mixture is subsequently stirred for 16 hours, during which
it is warmed to room temperature. The solid is isolated by
filtration and washed with twice 25 ml of absolute hexane. After
drying under reduced pressure, 2.1 g of hydrogenated
polygermasilane are isolated.
[0051] Our compositions and methods are not restricted by this
description on the basis of the working examples. Instead, this
disclosure encompasses every new feature and also every combination
of features which includes, in particular, any combination of
features in the appended claims, even if that feature or that
combination is itself not explicitly specified in the claims or
working examples.
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