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Silicon Info: Growth Methods - A Comparison
The
table summarizes some of the technological characteristics of the methods
used to grow silicon crystals for photovoltaic applications. A variety of approaches have viability for further development,
which is a strong point for Si PV commercial growth. Cost-driven tradeoffs are made in Si PV
crystal-growth technology. This is evident in both the ingot and sheet-growth approaches.
For example, the highest throughput ingot method, electromagnetic
casting, yields lower cell efficiencies than the slower CZ growth method
because of smaller grain sizes.
A similar situation exists with ribbons and sheets, where substrate
melt shaping has tremendous throughput potential.
Again, the grain size and cell efficiency are smaller than for some
of lower throughput ribbon methods.
The diversity and redundancy in approaches is healthy for the
industry and increases the probability that further reductions in PV
module cost will be achieved.
Method
|
Width
(cm)
|
Weight
(kg)
|
Growth
Rate
(mm/min)
|
Growth
Rate
(kg/h)
|
Throughput
(m2/day)*
|
Energy
Use
(kWh/kg)
|
Energy
Use
(kWh/m2)**
|
Efficiency
(Typical,
best %)
|
|
Float Zone
|
15
|
50
|
2-4
|
4
|
80
|
30
|
36
|
<18,
24
|
|
Czochralski
|
15
|
50
|
0.6-1.2
|
1.5
|
30
|
18-40
|
21-48
|
<15,
20
|
|
Directional Solidification
|
69
|
240
|
0.1-0.6
|
3.5
|
70
|
8-15
|
9-17
|
<14,
18
|
|
Electromagnetic Casting
|
35
|
400
|
1.5-2
|
30
|
600
|
12
|
35
|
<14,
16
|
|
Dendritic Web
|
5
|
--
|
12-20
|
--
|
1
|
--
|
200
|
<15,
17
|
|
Capillary Die Growth
|
80
|
--
|
15-20
|
--
|
20
|
--
|
20
|
14,
16
|
|
Edge-Supported Pulling
|
8
|
--
|
12-20
|
--
|
1.7
|
--
|
55
|
<13,
16
|
|
Substrate Melt Shaping
|
20
|
--
|
1000-6000
|
--
|
>1000
|
--
|
--
|
<12,
16
|
|
Thin-Layer Si
|
2
|
--
|
10-3
^
|
--
|
--
|
--
|
--
|
--, 13
|
*Areal throughput for ingots assumes 20 wafers/cm
**Only the energy for growth is
included
-- indicates data are not available or not appropriate
^ deposition rate perpendicular to the substrate
|
