Method for producing a solar cell
A method for producing a solar cell, including the following steps: a) providing a substrate having a front side and a back side in a deposition apparatus, and b) coating the substrate in situ with two layers, including b1) oxidizing, by exposing the substrate to an oxygen-containing gas and a first plasma, to create an oxide layer and b2) subsequently depositing a silicon layer or SiC layer by exposure to a gas containing silicon, an optional gas containing carbon and a second plasma, wherein step b) is carried out under vacuum in the deposition apparatus and the vacuum is maintained continuously during step b).
1 . A method for producing a solar cell, comprising steps as follows:
a) providing a substrate having a front side and a back side in a deposition apparatus, and
b) coating the substrate in situ with two layers, comprising:
b1) oxidizing the substrate by exposing it to an oxygen-containing gas and to a first plasma, to generate an oxide layer, or depositing the oxide layer by PECVD, and
b2) subsequently depositing a silicon layer or SiC-layer by exposure to a silicon-containing gas, an optional carbon-containing gas and a second plasma,
wherein step b) is carried out under vacuum in the deposition apparatus and the vacuum is maintained throughout step b); and
wherein step b) is carried out with a low-pressure plasma having a pressure in a range from 0.1 to 5.0 mbar or 0.1 to 10.0 mbar and/or step b) is carried out with a low-pressure glow discharge having an excitation frequency in a range from 10 to 500 kHz or 30 to 50 kHz and/or in step b) the plasma is pulsed in a range with a duty cycle of T on /(T on +T off )<10% and/or in a range of T on =1 to 100 ms.
2 . The method as claimed in claim 1 , wherein the back side is subjected to steps a) and b).
3 . The method as claimed in claim 1 , wherein between steps b1) and b2) the substrate is not moved spatially within the deposition apparatus.
4 . The method as claimed in claim 1 , wherein:
the oxygen-containing gas is selected from a group consisting of:
O 2 ,
a gas mixture of O 2 /inert gas, the inert gas being preferably Ar, Ne, Kr or N 2 ,
an oxygen-containing molecular gas, which is preferably N 2 O, CO 2 , NO 2 , NO or CO, and
a layer-forming gas mixture, the layer-forming gas mixture being preferably SiH 4 /O 2 , SiH 4 /CO 2 , AlC 3 H 9 /N 2 O or AlC 3 H 9 /N 2 O/Ar,
and/or:
the silicon-containing gas and the optional carbon-containing gas are selected from the group consisting of a gas mixture of SiH 4 /H 2 , a gas mixture of SiH 4 /H 2 /PH 3 , a gas mixture of SiH 4 /H 2 /B 2 H 6 , a gas mixture of SiH 4 /CH 4 , a gas mixture of SiH 4 /CH 4 /PH 3 or a gas mixture of SiH 4 /CH 4 /B 2 H 6 .
5 . The method as claimed in claim 4 , wherein the oxygen-containing molecular gas is N 2 O, CO 2 , NO 2 , NO or CO.
6 . The method as claimed in claim 4 , wherein the layer-forming gas mixture is SiH 4 /O 2 , SiH 4 /CO 2 , AlC 3 H 9 /N 2 O or AlC 3 H 9 /N 2 O/Ar.
7 . The method as claimed in claim 4 , wherein the inert gas is Ar, Ne, Kr or N 2 .
8 . The method as claimed in claim 1 , wherein step b1) is carried out with a deposition rate of <0.2 nm/s or <0.1 nm/s and/or step b1) is carried out with a duty cycle<5% and/or step b1) is carried out at a temperature<500° C. or in a range from 300 to 450° C.
9 . The method as claimed in claim 8 , wherein two or more substrates are arranged in a boat in which pairs of substrates are arranged oppositely and have a different polarity.
10 . The method as claimed in claim 1 , wherein two or more substrates are subjected simultaneously to steps a) and b).
11 . The method as claimed in claim 1 , wherein the oxide layer generated in step b1) is configured as a tunnel layer and/or the solar cell is a TOPCon solar cell.
12 . The method as claimed in claim 1 , wherein the method is carried out as a direct plasma process or as a remote plasma process with a capacitive plasma as radiofrequency plasma or with an excitation frequency of 13.56 MHz or multiples thereof.
13 . The method as claimed in claim 1 , wherein before step a) with the substrate first a wet-chemical treatment, then a doping for the front side and subsequently a further wet-chemical treatment are carried out and after step b) with the substrate an annealing, then yet a further wet-chemical treatment of the front side, subsequently a passivation of the front side and of the back side and then a metallization of the front side and of the back side are carried out.
14 . The method as claimed in claim 1 , wherein the deposition apparatus is a tube furnace.
15 . A method for producing a solar cell, comprising steps as follows:
a) providing a substrate having a front side and a back side in a deposition apparatus, and
b) coating the substrate in situ with two layers, comprising:
b1) oxidizing the substrate by exposing it to an oxygen-containing gas and to a first plasma, to generate an oxide layer, or depositing the oxide layer by PECVD, and
b2) subsequently depositing a silicon layer or SiC-layer by exposure to a silicon-containing gas, an optional carbon-containing gas and a second plasma,
wherein step b) is carried out under vacuum in the deposition apparatus and the vacuum is maintained throughout step b), and
wherein:
the oxygen-containing gas is selected from a group consisting of:
O 2 ,
a gas mixture of O 2 /inert gas, the inert gas being preferably Ar, Ne, Kr or N 2 ,
an oxygen-containing molecular gas, which is preferably N 2 O, CO 2 , NO 2 , NO or CO, and
a layer-forming gas mixture, the layer-forming gas mixture being preferably SiH 4 /O 2 , SiH 4 /CO 2 , AlC 3 H 9 /N 2 O or AlC 3 H 9 /N 2 O/Ar,
and/or:
the silicon-containing gas and the optional carbon-containing gas are selected from the group consisting of a gas mixture of SiH 4 /H 2 , a gas mixture of SiH 4 /H 2 /PH 3 , a gas mixture of SiH 4 /H 2 /B 2 H 6 , a gas mixture of SiH 4 /CH 4 , a gas mixture of SiH 4 /CH 4 /PH 3 or a gas mixture of SiH 4 /CH 4 /B 2 H 6 .
16 . The method as claimed in claim 15 , wherein the inert gas is Ar, Ne, Kr or N 2 .
17 . The method as claimed in claim 15 , wherein the oxygen-containing molecular gas is N 2 O, CO 2 , NO 2 , NO or CO.
18 . A method for producing a solar cell, comprising steps as follows:
a) providing a substrate having a front side and a back side in a deposition apparatus, and
b) coating the substrate in situ with two layers, comprising:
b1) oxidizing the substrate by exposing it to an oxygen-containing gas and to a first plasma, to generate an oxide layer, or depositing the oxide layer by PECVD, and
b2) subsequently depositing a silicon layer or SiC-layer by exposure to a silicon-containing gas, an optional carbon-containing gas and a second plasma,
wherein step b) is carried out under vacuum in the deposition apparatus and the vacuum is maintained throughout step b); and
wherein step b1) is carried out with a deposition rate of <0.2 nm/s or <0.1 nm/s and/or step b1) is carried out with a duty cycle<5% and/or step b1) is carried out at a temperature<500° C. or in a range from 300 to 450° C.
19 . The method as claimed in claim 18 , wherein two or more substrates are arranged in a boat in which pairs of substrates are arranged oppositely and have a different polarity.
20 . The method as claimed in claim 18 , wherein two or more substrates are subjected simultaneously to steps a) and b).