JP2001064007A - Ga-ADDED POLYCRYSTALLINE SILICON, Ga-ADDED POLYCRYSTALLINE SILICON WAFER AND ITS PRODUCTION - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a solar battery which is free from photo-deterioration and stable in photo-energy conversion efficiency by adding Ga as a dopant. SOLUTION: An objective material for the solar battery is Ga-added polycrystalline silicon and the concentration of the Ga in the crystal is preferably 3×1014 to 2×1017 atom/cm3. Though p-type polycrystalline silicon in which B is mainly doped has been used as the polycrystalline silicon for the silicon solar battery, when the polycrystalline, wherein Ga is added in place of B, is used as the substrate of the solar battery, it becomes possible to produce a solar battery which is stable in the conversion efficiency without being affected by the photo-deterioration. The method for adding Ga into a silicon molten liquid in a crucible comprises previously growing a silicon crystal in which Ga is added in a high concentration, then crushing the silicon crystal doped with Ga in high concentration to prepare a dopant and adding the obtained dopant into the silicon molten liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to polycrystalline silicon, a polycrystalline silicon wafer, a method for producing the same, and a polycrystalline silicon solar cell using the same, which are particularly useful as materials for solar cells.

[0002]

2. Description of the Related Art First, characteristics of a solar cell will be described based on a substrate material constituting the solar cell. When a solar cell is classified by its substrate material, it can be broadly classified into three types: a silicon crystalline solar cell, an amorphous silicon solar cell, and a compound semiconductor solar cell. Solar cells include “single-crystal silicon-based solar cells” and “polycrystalline silicon-based solar cells”. Among these, a solar cell having a high conversion efficiency, which is the most important characteristic as a solar cell, is a "compound semiconductor-based solar cell", and its conversion efficiency reaches nearly 25%. However, it is very difficult to make a compound semiconductor as a material for the compound semiconductor-based solar cell, and there is a problem that the solar cell substrate is widely used in terms of manufacturing cost, and its use is limited. I have.

[0003] Here, the "conversion efficiency" is a value indicating the "ratio of energy which can be converted into electric energy by the solar cell and taken out by the solar cell with respect to the energy of light incident on the solar cell". , More specifically, a value defined by the following equation. [Conversion efficiency] = [power that could be taken out per cell unit area] / [light energy irradiated per cell unit area] × 100 (%)

As a solar cell having the second highest conversion efficiency after a compound semiconductor solar cell, a single crystal silicon solar cell follows, and its power generation efficiency is about 20%, which is close to that of a compound semiconductor solar cell. However, such a single crystal silicon solar cell also has a drawback that the raw material cost occupies almost half of the entire production cost, and it is difficult to reduce the cost. Therefore, although the conversion efficiency is about 5 to 15%, which is inferior to the above two solar cells, the production cost of the solar cell substrate material is low, so that a polycrystalline silicon-based solar cell has been put into practical use. It is the most manufactured solar cell today.

Next, a method for manufacturing a general polycrystalline silicon solar cell will be briefly described. First, in order to obtain a silicon wafer serving as a solar cell substrate, a crucible such as quartz is filled with semiconductor-grade silicon, and the crucible is heated in a heating region to melt the silicon in the crucible. The polycrystalline silicon is grown by pulling it down from the heating area and cooling it to produce a polycrystalline silicon ingot. Furthermore, this ingot is sliced and processed into a thin wafer having a thickness of, for example, about 300 μm.
A wafer (substrate) serving as a solar cell can be obtained by removing the processing strain on the surface by etching the wafer surface with a chemical solution. Impurities (dopants) in this wafer
After forming a PN junction surface on one side of the wafer by performing a diffusion process, an anti-reflection film is applied to the surface on the sunlight incident side to reduce the loss of light energy due to the reflection of light. Finally, electrodes are formed on both surfaces of the wafer. To complete the solar cell.

[0006] Recently, the demand for solar cells is increasing as one of the clean energy due to environmental problems.
The high energy cost compared to general commercial power is an obstacle to its spread. In order to reduce the cost of silicon crystal solar cells, it is important to reduce the manufacturing cost of the substrate, and it can be said that a polycrystalline silicon solar cell capable of manufacturing a substrate at low cost satisfies those requirements. .

However, on the other hand, it is important to further increase the conversion efficiency of the solar cell. Since a solar cell separates a carrier generated by light by an internal electric field to generate an electromotive force, it is desirable that the lifetime of the generated carrier be long. If the lifetime of the carrier is long, high conversion efficiency can be obtained.

However, polycrystalline silicon produced by melting, cooling, and solidifying semiconductor-grade silicon, which is the mainstream in the current method of producing polycrystalline rods, has a problem in terms of conversion efficiency when a solar cell is manufactured from this. there were. That is,
When a certain period of time has passed after irradiating such a solar cell with strong light, the lifetime of carriers in the solar cell substrate is reduced. For this reason, the conversion efficiency is reduced, and a sufficient conversion efficiency cannot be obtained stably, and improvement is required from the viewpoint of the performance of the solar cell.

[0009]

When a solar cell is manufactured using this polycrystalline silicon, the lifetime decreases and the conversion efficiency decreases when a long time elapses after strong light is applied to the solar cell. It is known that the influence is caused by boron and oxygen existing in the polycrystalline substrate. At present, P-type is the main type of wafer used as a solar cell, and boron is usually added to this P-type wafer as a dopant, and oxygen is also present in the polycrystalline silicon crystal. I do. For this reason, there is a problem that the lifetime characteristics are affected by boron and oxygen in the P-type polycrystalline silicon and light degradation occurs.

On the other hand, since a wafer used for a solar cell is desirably a wafer having as low a resistance as possible, it is not preferable to reduce the boron doping amount so much. Furthermore, oxygen is inevitably taken in in order to increase the purity of polycrystalline silicon in order to increase the purity of polycrystalline silicon in order to use quartz in the manufacture thereof and to hold a silicon melt therein. Further, if the oxygen concentration in the crystalline silicon is too low, the mechanical strength of the crystalline silicon is impaired. For this reason, conventionally, there has been a problem that a solar cell obtained using polycrystalline silicon has a low conversion efficiency and is unstable when used for a long time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made in view of the above-mentioned circumstances, and has been made of a polycrystalline silicon and a polycrystalline silicon wafer for producing a solar cell having a stable light energy conversion efficiency without causing photodegradation. The purpose is to provide a method for producing them.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above-mentioned object, and the invention described in claim 1 of the present invention is a polycrystalline silicon having a Ga content as a dopant. Polycrystalline silicon to which (gallium) is added.

Until now, P-type polycrystalline silicon doped with boron (hereinafter sometimes referred to as boron or B) has been mainly used as polycrystalline silicon for silicon solar cells. If a polycrystal to which is added is used as a solar cell substrate, a stable solar cell with high conversion efficiency can be produced without being affected by light deterioration when processed into a solar cell.

According to a second aspect of the present invention, there is provided the polycrystalline silicon to which the Ga is added, wherein the concentration of Ga contained in the crystal is 3 × 10 ¹⁴ atoms / cm ³ to 2
It is polycrystalline silicon characterized by having a density of × 10 ¹⁷ atoms / cm ³ .

This is because a substrate having a low resistivity and a long lifetime is desired as a substrate for a solar cell, but a substrate having an extremely low resistivity of a substrate wafer has an auger (A) inside the substrate.
Auger) recombination results in a reduction in lifetime and a reduction in conversion efficiency. Therefore, the amount of gallium contained in the polycrystalline silicon of the present invention is 2 × 10 ¹⁷ atoms /
cm ³ or less is preferable. On the other hand, if the substrate resistivity is too high, a problem occurs. This is because, when the substrate resistivity is high, power is consumed by the internal resistance of the solar cell when the solar cell is used, and the conversion efficiency is similarly reduced. For these reasons, if it is used as a substrate material for a solar cell, the concentration of gallium in the polycrystal is 3 × 10
^It is good to be ¹⁴ atoms / cm ³ or more.

The invention according to claim 3 of the present invention is a Ga-added polycrystalline silicon wafer obtained by slicing the Ga-added polycrystalline silicon. If such a Ga-doped polycrystalline silicon wafer is used as a substrate material for a solar cell, a decrease in carrier lifetime caused by the influence of oxygen contained in the crystal can be suppressed. Even with a silicon wafer, it is possible to obtain a long lifetime required for a solar cell. As a result, it is possible to obtain an appropriate lifetime even in a cell having a low resistivity, and it is possible to manufacture a high-performance solar cell without impairing conversion efficiency even in a solar cell using a substrate wafer having a high oxygen concentration. became.

As described above, the Ga-doped polycrystalline silicon and the Ga-doped polycrystalline silicon wafer of the present invention are particularly useful when used for solar cells (claims 4 and 5). Also, a polycrystalline silicon solar cell manufactured from such a Ga-doped polycrystalline silicon or a Ga-doped polycrystalline silicon wafer can be inexpensive and have high energy conversion efficiency (claims 6 and 7). ).

That is, for example, by processing a Ga-doped polycrystalline silicon ingot into a solar cell substrate and manufacturing a solar cell from the wafer, a solar cell having stable conversion efficiency even when irradiated with strong light for a long time is manufactured. can do. When Ga-doped polycrystalline silicon is used as a material for a solar cell, the lifetime of carriers in the substrate can be stabilized, so that a solar cell with high conversion efficiency can be manufactured.

In the conventional boron-doped polycrystalline silicon, when the resistivity is lowered by doping a large amount of boron, the lifetime of carriers after long-time use is reduced, and the conversion efficiency is stably increased. A solar cell with low resistivity could not be manufactured. However, by using the Ga-doped polycrystalline silicon and the Ga-doped polycrystalline silicon wafer of the present invention, a solar cell having high long-term conversion efficiency and low resistivity can be manufactured.

Next, according to an eighth aspect of the present invention, in the method for producing polycrystalline silicon, after adding Ga to a silicon melt in a crucible heated and melted, the silicon melt is cooled. This is a method for producing Ga-doped polycrystalline silicon, which comprises growing polycrystalline silicon. Thus, Ga-doped polycrystalline silicon can be manufactured.

In this case, as described in claim 9, the addition of Ga to the silicon melt in the crucible is performed by growing a silicon crystal to which a high concentration of Ga has been added in advance and removing the high concentration Ga-doped silicon crystal. It is preferable to add Ga to the silicon melt using a crushed dopant.

As a method of doping Ga in the case of manufacturing a polycrystal to which Ga is added in the present invention, gallium may be directly added before melting polycrystalline silicon or in a molten silicon melt. If the polycrystal to which is added is industrially mass-produced, it is better to dope after once adjusting the dopant as described above. By using such a method, work can be performed efficiently. This is because the amount of Ga to be added is extremely small compared to the amount of silicon, and the melting point of gallium is as low as 30 ° C., which makes handling difficult. Therefore, by using a method of doping after preparing a dopant, rather than directly putting gallium into the crucible, it is possible to easily and accurately adjust the Ga concentration and obtain an accurate dopant concentration. In addition, the handling of the dopant itself becomes easier as compared with the case where gallium is directly injected into the silicon melt, which also leads to an improvement in workability.

Hereinafter, the present invention will be described in detail.
The present invention is not limited to these. The present inventors have conducted intensive research and experiments on how to obtain a substrate having relatively high conversion efficiency as a solar cell, which is relatively easy to manufacture and mass-producible as a solar cell substrate material. As a result of repeated studies, the present invention has been completed.

Conventional P doped with boron as a dopant
Solar cells made from polycrystalline silicon of the type
It is considered that the reason why the conversion efficiency is reduced by long-time light irradiation is that a complex of boron and oxygen is generated by the light irradiation and becomes a recombination center of carriers. That is, due to the simultaneous presence of oxygen and boron in the crystal, the energy level at the PN junction surface of the solar cell changes, and a deep energy level (also referred to as a deep level or a trap level) is formed at the junction surface. ,
It has been considered that the carrier in the solar cell is captured at this deep energy level, which causes a reduction in the lifetime of the carrier (Investigation o).
f carrier lifetime instab
illites in CZ ・ grown silic
on, Jan Schmidt et al, 26th
IEEE Photovoltaic specia
lists conference, 1997).

Therefore, the inventors of the present invention have found that the lifetime of the substrate is reduced only when oxygen and boron are present at the same time, and that the lifetime is not changed with either oxygen or boron alone, and that photodegradation occurs. Focusing on the fact that there is no such element, the present inventors have conceived of making P-type polycrystalline silicon using elements other than boron, and have completed the present invention.

Although the present inventors have mainly used a P-type silicon wafer for a solar cell substrate, if P-type polycrystalline silicon can be produced using an element other than boron, oxygen is contained in the crystal. Even if it is present, it is thought that a solar cell with small light degradation can be manufactured without a decrease in the substrate lifetime, and as a result of repeating the experiment, gallium was added as a dopant to produce P-type polycrystalline silicon, From this, a solar cell substrate was fabricated, and it was confirmed that a solar cell using this could always produce a solar cell with a stable lifetime and no reduction in conversion efficiency even if a high concentration of oxygen was present in the crystal. did.

As a result, even if polycrystalline silicon has a high oxygen concentration, it is possible to stably produce a solar cell having high conversion efficiency without causing photodegradation even when used for a long time. The power generation cost by the crystalline silicon solar cell can be reduced. As a result, it greatly contributes to solving the cost problem of the silicon raw material for solar cells.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited thereto. First, an example of the configuration of a polycrystal manufacturing apparatus used in the present invention will be described with reference to FIG. As shown in FIG. 1, the polycrystalline manufacturing apparatus 1 includes a chamber 2 for accommodating a crucible 3 for melting a raw material and the like. The chamber 2 is provided with a raw material supply port 9 for supplying a raw material into the apparatus. The raw material such as silicon and Ga is supplied from the raw material supply port 9 as needed. Further, an exhaust port 10 is provided in the chamber 2, and the exhaust port 10 is connected to a vacuum pump (not shown) so that the pressure in the chamber can be reduced to a predetermined pressure.

The crucible 3 in the chamber 2 comprises a quartz crucible 4 on the inside and a graphite crucible 5 on the outside. Around the crucible 3 and above, a heater 6 for heating and melting the raw material silicon charged in the crucible is arranged so as to surround the crucible 3 to form a heating region. Further, the heater 6 is surrounded by a heat shield plate 7, and the heat shield plate 7 is also arranged at the bottom of the crucible 3 to prevent the radiation heat from the heater 6 from escaping. The inside of the crucible is filled with a melt L of silicon dissolved by heating with the heater 6. The crucible 3 is supported by a crucible support shaft 8 that can move up and down. The distance between the crucible 3 and the heating area formed by the heater 6 can be changed by moving the crucible support shaft 8 up and down.

Next, a method for producing polycrystalline silicon using the above-described apparatus will be described. First of all, quartz crucible 4
A release agent is applied to the inner wall of the substrate so that the grown polycrystalline silicon can be easily removed from the crucible. Next, the polycrystalline silicon material and Ga as a dopant are put in the quartz crucible 4 and heated by the heater 6 to melt the material. Here, when adding Ga, crystalline silicon to which Ga is added at a high concentration is prepared in advance, and then finely crushed to prepare a dopant, and the dopant is added to a desired concentration when melting the polycrystalline silicon. It is desirable to adjust the input so that
The amount of Ga to be added is extremely small compared to silicon,
Since the melting point of Ga is as low as 29.8 ° C., it is difficult to weigh accurately. However, in this case, the amount to be weighed is increased and the problem of the melting point is eliminated, so that the weighing can be performed more accurately. During the melting of the raw material, the pressure in the chamber 2 is reduced to a predetermined pressure, and is kept in a clean state.

Next, when all of the polycrystalline silicon material is melted, the crucible 3 is pulled down from the heating area formed by the heater 6 at a speed of about 0.05 to 0.20 mm / min and cooled. In the crucible 3, the melt L starts to solidify from the bottom of the crucible in which the cooling proceeds rapidly. Then, as the crucible 3 is pulled down from the heating region, columnar polycrystalline silicon is grown in the crucible 3. When all of the silicon melt L in the crucible 3 has crystallized, a columnar polycrystalline silicon ingot is taken out of the crucible.

Thus, polycrystalline silicon to which Ga is added as a dopant can be obtained. Next, the polycrystalline silicon ingot is made according to the usual method,
The wafer is sliced by a cutting device such as an inner peripheral blade slicer or a wire saw and processed into a polycrystalline silicon wafer. Of course, these steps are not limited to those listed above, and there may be various other steps such as washing, and the steps may be changed and used as appropriate according to the purpose, such as changing the order of the steps or partially omitting the steps.

The obtained polycrystalline silicon wafer is subjected to, for example, an impurity (dopant) diffusion treatment to form a PN junction surface on one side of the wafer. A solar cell is completed by forming an anti-reflection film to reduce the loss of the solar cell and finally forming electrodes on both sides.

[0034]

EXAMPLES Hereinafter, specific embodiments of the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. (Example) Polycrystalline silicon doped with Ga as a dopant was produced using a polycrystalline production apparatus as shown in FIG. 1, and a solar cell was produced from a wafer produced from this polycrystalline silicon. And its conversion efficiency was measured.

First, a Ga dopant was prepared. 5 kg of semiconductor grade silicon and 50 g of Ga, 15 cm in diameter,
It was placed in a 25 cm deep quartz crucible, melted in a clean electric furnace, and quenched to produce a silicon crystal doped with a high concentration of Ga. The crystal had many cracks due to shrinkage upon cooling, and the quartz crucible used for the container had adhered to the crystal, which was carefully removed. Thereafter, the high-concentration Ga-doped silicon crystal was pulverized and washed with hydrofluoric acid to prepare a high-concentration Ga doping agent. When this Ga dopant was analyzed, the Ga concentration was 8.6 × 10 ¹⁹ at.
oms / g.

Next, a polycrystal manufacturing apparatus 1 as shown in FIG.
Was used to produce Ga-doped polycrystalline silicon. 5 kg of semiconductor-grade silicon and 25 g of the above-mentioned Ga dopant are put into a quartz crucible 4 having a diameter of 15 cm and a depth of 25 cm to which a mold release agent has been applied, and heated and melted by a heater 6. It was pulled down from the heating area and cooled to produce columnar polycrystalline silicon. When a rectangular parallelepiped of 5 cm square and 2 cm thick was cut out from the center of the crystal ingot thus manufactured, the resistivity was 1.1 Ω.
Cm. Further, this rectangular parallelepiped crystal was sliced perpendicularly to the direction of the crystal developed in a columnar shape, to produce a polycrystalline silicon wafer.

This 5 cm square Ga-doped wafer was treated with Na
The work-strained layer was removed by immersion in an OH solution, and then a sheet resistance of 78Ω / □ and a depth of 0.2 μm was obtained by a diffusion method using POCl _3.
A PN junction having a shallow depth was formed. Then on the surface of the wafer,
An SiO ₂ passivation film for surface stabilization and a TiO ₂ film as an antireflection film were sequentially laminated. Then, after removing an excess diffusion layer on the back surface by etching, printing and baking of an Al paste is performed to form a BSF (back surface).
(ce field) layer was formed. Electrodes are formed on the front and back surfaces of the wafer by printing and baking an Ag paste, respectively.
The solar cell was completed by depositing a gF ₂ film.

The conversion efficiency of the solar cell thus obtained was measured. The conversion efficiency was measured by placing a solar cell on a measuring table whose temperature was adjusted to 25 ° C., and using a solar simulator using a halogen lamp as a light source, AM (air mass).
The cell was irradiated with steady light under the conditions of 1.5, and the voltage and current that could be extracted from the cell were measured to calculate the conversion efficiency of the solar cell.

When the conversion efficiency of the solar cell was measured in this way, it showed a high value of 16.3%, indicating that light energy was efficiently converted to electric energy. After continuously irradiating the solar cell with light of AM1.5 for 30 hours under a solar simulator, the conversion efficiency was measured again. As a result, the conversion efficiency was 16.3%. showed that.

(Comparative Example) Polycrystalline silicon to which B was added as a dopant was produced using a polycrystalline production apparatus as shown in FIG. 1, and a solar cell was fabricated using a wafer produced from this polycrystalline silicon. It was manufactured and its conversion efficiency was measured.

That is, B-doped polycrystalline silicon was produced using the polycrystalline manufacturing apparatus 1 as shown in FIG.
5 kg of semiconductor-grade silicon and 25 g of B dopant containing boron are put into a quartz crucible 4 having a diameter of 15 cm and a depth of 25 cm to which a release agent is applied, and heated and melted by a heater 6. Then, the column was pulled down from the heating region at a rate of / min and cooled to produce columnar polycrystalline silicon. A rectangular parallelepiped of 5 cm square and 2 cm thick was cut out from the center of the crystal ingot thus manufactured, and the resistivity was 1.0 Ω · cm. Further, this rectangular parallelepiped crystal was sliced perpendicularly to the direction of the crystal developed in a columnar shape, to produce a polycrystalline silicon wafer.

From this 5 cm square B-doped wafer, a solar cell was manufactured in the same process as in the above-described embodiment.
When the conversion efficiency of the solar cell thus manufactured was measured by the same method as in the example, the conversion efficiency was 16.2% immediately after the start of the measurement, which was almost the same as the example. However, after continuously irradiating this solar cell with AM1.5 light for 30 hours under a solar simulator, the conversion efficiency was measured again.
The conversion efficiency was reduced to 5.9%.

The present invention is not limited to the above embodiment. The above embodiment is an exemplification, and has substantially the same configuration as the technical idea described in the scope of the claims of the present invention. It is included in the technical scope of the invention.

For example, in the above embodiment, the polycrystalline silicon is manufactured by lowering the crucible containing the silicon melt from the heating area to manufacture the polycrystalline silicon. However, the present invention is not limited to this. Absent. For example, it is possible to grow the polycrystalline silicon from the crucible bottom by cooling the crucible bottom with a heat exchanger or the like while keeping the crucible fixed in the heating area.
Alternatively, instead of manufacturing a column-shaped polycrystalline ingot, a flat wafer-shaped polycrystal may be manufactured from the beginning. In any method, a method for producing a polycrystal by adding Ga to a silicon melt and then cooling the silicon melt is included in the scope of the present invention.

[0045]

According to the present invention, a polycrystalline silicon and a polycrystalline silicon wafer are doped with Ga to produce a polycrystalline silicon for producing a solar cell having a very high light energy conversion efficiency without causing photodegradation. And a polycrystalline silicon wafer.

[Brief description of the drawings]

FIG. 1 is a structural example of a polycrystal manufacturing apparatus used in the present invention.

[Explanation of symbols]

1. Polycrystalline manufacturing equipment 2. Chamber 3. Crucible
4: quartz crucible, 5: graphite crucible, 6: heater,
7: heat shield plate, 8: crucible support shaft, 9: raw material supply port,
10: exhaust port, L: silicon melt.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Teruhiko Hirasawa 2-13-1 Isobe, Annaka-shi, Gunma F-term in Shin-Etsu Kagaku Kogyo Co., Ltd. Precision Materials Research Laboratories 4G072 AA01 BB12 GG01 HH01 JJ07 MM38 NN01 QQ09 RR12 UU02 5F051 AA03 CB04 DA03 HA01 5F053 AA11 BB04 BB13 DD01 FF04 GG02 JJ01 LL05 RR07

Claims (9)

[Claims] 1. A polycrystalline silicon, wherein Ga (gallium) is added as a dopant. 2. The polycrystalline silicon to which Ga is added, wherein the concentration of Ga contained in the crystal is 3 × 10 ¹⁴ at.
2. The polycrystalline silicon according to claim 1, wherein the polycrystalline silicon is oms / cm ^{3 to} 2 × 10 ¹⁷ atoms / cm ³ . 3. A Ga-added polycrystalline silicon wafer obtained by slicing the polycrystalline silicon according to claim 1 or 2. 4. The Ga-doped polycrystalline silicon according to claim 1, wherein the polycrystalline silicon is for a solar cell. 5. The Ga-doped polycrystalline silicon wafer according to claim 3, wherein the wafer is for a solar cell. 6. A polycrystalline silicon solar cell produced from the Ga-doped polycrystalline silicon according to claim 1. 7. A polycrystalline silicon solar cell produced from the Ga-doped polycrystalline silicon wafer according to claim 3. 8. A method for producing polycrystalline silicon, characterized in that after adding Ga to a silicon melt in a crucible heated and melted, the silicon melt is cooled to grow polycrystalline silicon. A method for producing Ga-doped polycrystalline silicon. 9. The addition of Ga to the silicon melt in the crucible is performed by growing a silicon crystal to which high-concentration Ga is added in advance and using a doping agent formed by crushing the high-concentration Ga-doped silicon crystal. 9. The method for producing Ga-doped polycrystalline silicon according to claim 8, wherein Ga is added to the silicon melt.