METHOD FOR MANUFACTURING A MULTILAYER OF A TRANSPARENT CONDUCTIVE OXIDE
A multi-part transparent conductive zinc oxide layer for a photoelectric conversion device, and a method of producing same. The transparent conductive zinc oxide layer includes at least one basic layer sequence with a varying boron dopant concentration. The basic layer sequence includes a thinner transparent conductive zinc oxide higher-boron-doped layer and a thicker transparent conductive zinc oxide lower-boron-doped layer. The doping density through each individual conductive zinc oxide layer is substantially constant, which is achieved by intentionally doping the thicker transparent conductive zinc oxide lower-boron-doped layer. Optionally, an interlayer may be present between the at least one basic layer sequence and the substrate or an n-doped silicon layer upon which it is disposed. This advantageously permits efficient Edge Isolation by Laser EIL ablation of the transparent conductive zinc oxide layers while maintaining good electrical and optical properties in said layers.
1 . An electrode for a photoelectric conversion device comprising:
at least one basic layer sequence having a varying boron dopant concentration;
said basic layer sequence comprising a thinner transparent conductive zinc oxide higher-boron-doped layer and a thicker transparent conductive zinc oxide lower-boron-doped layer;
wherein the doping density through each individual conductive zinc oxide layer is substantially constant.
2 . An electrode according to claim 1 , wherein said electrode comprises a plurality of said basic layer sequences.
3 . An electrode according to claim 1 , further comprising a substrate, wherein the electrode is a front electrode and is arranged on the substrate, said substrate comprising glass.
4 . An electrode according to claim 3 , further including an interlayer disposed between the at least one basic layer sequence and the substrate.
5 . An electrode according to claim 3 , wherein the basic layer sequence is arranged in direct and intimate contact with said substrate.
6 . An electrode according to claim 1 , wherein the electrode is a back electrode and is arranged on an n-doped silicon layer.
7 . An electrode according to claim 6 , further including an interlayer disposed between the at least one basic layer sequence and the n-doped silicon layer.
8 . An electrode according to claim 6 , wherein the basic layer sequence is arranged in direct and intimate contact with the n-doped silicon layer.
9 . An electrode according to claim 1 , wherein the thinner transparent conductive zinc oxide higher-boron-doped layer is arranged directly adjacent to a substrate or to an n-doped silicon layer or to an interlayer between the basic layer and a substrate.
10 . An electrode according to claim 4 , wherein a doping concentration of the interlayer is lower than that of the thinner transparent conductive zinc oxide higher-born-doped layer.
11 . A method for manufacturing an electrode for a photoelectric conversion device comprising:
depositing on a substrate or on an n-doped silicon layer at least one basic layer sequence having a varying boron dopant concentration;
wherein said basic layer sequence comprises a thinner transparent conductive zinc oxide higher-boron-doped layer and a thicker transparent conductive zinc oxide lower-boron-doped layer; and
wherein said thicker transparent conductive zinc oxide lower-boron-doped layer is intentionally doped.
12 . A method according to claim 11 , further comprising depositing an interlayer such that it is disposed between the substrate or the n-doped silicon layer and the at least one basic layer sequence.
13 . A method according to claim 11 , wherein a plurality of basic layer sequences are deposited on the substrate or on the n-doped silicon layer.
14 . A method according to claim 11 , wherein the basic layer sequence is deposited according to the following steps:
depositing on the substrate or the n-doped silicon layer a first transparent conductive zinc oxide layer;
depositing on said first transparent conductive zinc oxide layer a second transparent conductive zinc oxide layer,
wherein the first transparent conductive zinc oxide layer is one of the thinner transparent conductive zinc oxide higher-boron-doped layer and the thicker transparent conductive zinc oxide lower-boron-doped layer, and
wherein the second conductive zinc oxide layer is the other of the thinner transparent conductive zinc oxide higher-boron-doped layer and the thicker transparent conductive zinc oxide lower-boron-doped layer.
15 . A method according to claim 11 , wherein the electrode is deposited according to the following steps:
depositing an interlayer on the substrate or the n-doped silicon layer,
depositing on the interlayer a first transparent conductive zinc oxide layer,
depositing on said first transparent conductive zinc oxide layer a second transparent conductive zinc oxide layer;
wherein the first conductive zinc oxide layer is one of the thinner transparent conductive zinc oxide higher-boron-doped layer and the thicker transparent conductive zinc oxide lower-boron-doped layer, and the second transparent conductive zinc oxide layer is the other of the thinner transparent conductive zinc oxide higher-boron-doped layer and the thicker transparent conductive zinc oxide lower-boron-doped layer.
16 . A method according to claim 15 , wherein the first transparent conductive zinc oxide layer is the thinner transparent conductive zinc oxide higher-boron-doped layer and the second transparent conductive zinc oxide layer is the thicker transparent conductive zinc oxide lower-boron-doped layer.
17 . A method according to claim 11 , wherein the said layers at least one basic layer sequence is deposited by a vacuum processing method including at least one of Chemical Vapor Deposition, Low Pressure Chemical Vapor Deposition, Plasma Enhanced Chemical Vapor Deposition or Physical Vapor Deposition.
18 . A method according to claim 17 , wherein the thinner transparent conductive zinc oxide higher-boron-doped layer is deposited under conditions of a first diborane/diethyl zinc ratio of 0.1-1.
19 . A method according to claim 18 , wherein the thicker transparent conductive zinc oxide lower-boron-doped layer is deposited under conditions of a second diborane/diethyl zinc ratio of 0.01-0.2.
20 . A method according to claim 19 , wherein a ratio of the first diborane/diethyl zinc ratio to the second diborane/diethyl zinc ratio is between 2 and 60.
21 . A method according to claim 17 , wherein the transparent conductive zinc oxide layers are deposited under conditions of a H2O/diethyl zinc ratio of 0.8 to 1.5.
22 . A method according to claim 17 , wherein the temperature of the substrate during deposition is in a range of 150-220° C.
23 . A method according to claim 13 , further comprising the steps of depositing at least one further first transparent conductive zinc oxide layer and at least one further second transparent conductive zinc oxide layer so as to form a plurality of basic layer structures.
24 . A method according to claim 1 , wherein the thinner transparent conductive zinc oxide higher-boron-doped layer and the thicker transparent conductive zinc oxide lower-boron-doped layer are deposited in two separate, discrete processing steps.
25 . A method according to claim 19 , wherein the thinner transparent conductive zinc oxide higher-boron-doped layer and the thicker transparent conductive zinc oxide lower-boron-doped layer are deposited sequentially by varying the diborane/diethyl zinc ratio from the first diborane/diethyl zinc ratio to the second diborane/diethyl zinc ratio or from the second diborane/diethyl zinc ratio to the first diborane/diethyl zinc ratio over a time period of 30 seconds or less.
26 . A method according to claim 12 , wherein the doping concentration of the interlayer is lower than that of the thinner transparent conductive zinc oxide higher-born-doped layer.
27 . A method according to claim 17 , wherein the thinner transparent zinc oxide higher-boron-doped layer is deposited under conditions of a first diborane/diethyl zinc ratio of 0.2-0.55;
wherein the thicker transparent zinc oxide lower-boron-doped layer is deposited under conditions of a second diborane/diethyl zinc ratio of 0.02-0.1; and
wherein a ratio of the first diborane/diethyl zinc ratio to the second diborane/diethyl zinc ratio is between 7 and 10.