JPH11322500A - P-type semiconductor, its production and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a p-type semiconductor which is produced by using a Ib- IIIb-VIb2 compound semiconductor (particularly, CuInS2 ) as its base material and has a high carrier concn. and advantages with respect to both its production and performance. SOLUTION: The production of this semiconductor involves adding both N (a p-type impurity) and Zn (an n-type impurity) to CuInS2 to form p-type CuInS2 having e.g. 5×10<17> /cm<3> of carrier concn. value, which is higher as compared with 2×10<16> /cm<3> of the value obtained at the time of adding both N and In to CuInS2 and 1×10<15> /cm<3> of the value obtained at the time of adding only N to CuInS2 . Thus, by using this p-type semiconductor CuInS2 film contg. both N and Zn, as a p-type semiconductor layer 3 of a thin film type solar cell, in place of a p-type semiconductor CuInS2 film contg. only N, conversion efficiency of the solar cell can be enhanced, e.g. to a value about four times as high as the previous value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to Ib-IIIb-
The present invention relates to a p-type semiconductor in which an impurity is contained in a VIb Group ₂ compound semiconductor, and particularly to a high-performance p-type semiconductor which is suitable for a photovoltaic element such as a solar cell or a light emitting element.

[0002]

2. Description of the Related Art Compound semiconductors have been applied to semiconductor devices such as solar cells and light emitting devices. In the case of manufacturing these devices, a p-type semiconductor and an n-type semiconductor are required, and in order to obtain a semiconductor of each conductivity type, it is necessary to dope a compound semiconductor with an element other than its constituent elements. Will be

For example, Ib-IIIb such as CuInS ₂
In the case of a -VIb ₂ group compound semiconductor, it is known to add a Vb group element as an impurity to obtain a p-type and a VIIb group element as an impurity to obtain an n-type.

In the case of a IIIb-Vb compound semiconductor such as GaN, a group IIa element, n
Group IVb elements are used as impurities to obtain the mold,
In the case of a IIb-VIb compound semiconductor such as ZnSe, a Vb group element for obtaining p-type and a V-type element for obtaining n-type
Group IIb elements are used as impurities.

[0005] Such a compound semiconductor becomes conductive (p-type or n-type) when the added impurity replaces some of the constituent elements of the compound semiconductor.
In the case of forming a p-type semiconductor, generally, an element having one less number of outermost shell electrons than that of the constituent element to be replaced is selected as an impurity. One more element is selected as the impurity.

However, if a compound semiconductor is doped with a p-type impurity in order to obtain p-type conductivity, particularly in a compound semiconductor having a strong ionic bond, a negative element (element serving as an electron receiving side) constituting the compound semiconductor is removed. By exiting, the tendency of donor properties becomes stronger. As a result, the added p-type impurity is used to neutralize this strong donor property, and the p-type carrier concentration does not rise as expected. That is, there is a problem that it is difficult to obtain a p-type semiconductor having a high carrier concentration corresponding to a high doping amount.

If the amount of the p-type impurity is significantly increased in order to increase the carrier concentration, the crystallinity of the compound semiconductor serving as a base material is reduced, and the doping elements are segregated at crystal grain boundaries. However, there is also a problem that it is difficult to obtain necessary functions.

[0008] From these problems, a semiconductor device using a p-type semiconductor based on a compound semiconductor having a strong ionic bond as a base material, for example, a solar cell based on CuInS ₂ or the like,
As a blue light emitting device based on GaN, ZnSe, CuAlSe _2, etc., a device having sufficient performance has not been obtained.

Among these, with respect to a p-type semiconductor using GaN as a base material, a p-type semiconductor having a high carrier concentration can be formed by adding both Be as an acceptor and O as a donor to GaN. , Bra
ndt et al. (Appl. Phy.
s. Lett. , Vol. 69, no. 18 (199
6) See 2707). In this case, the impurity Be
Since the difference between the electronegativities of O and O is large, they are likely to be present in the vicinity in the GaN crystal, so that the carrier concentration increases.

Also, "The 1996 MRS Sp
ring Meeting Symposium in
In San Francisco ”, Yamamoto et al.
By substituting a part of Cu, which is a constituent element of CuInS ₂ , with In, C at the time of doping with a p-type impurity
It has been proposed to increase the p-type carrier concentration of CuInS _{2 by} supplying electrons to the u-S bond.

That is, when a part of Cu, which is a Group Ib element, is replaced by In, which is a Group IIIb element, and Cu <In, the number of electrons in CuInS _{2 is} larger than in the case where Cu: In = 1: 1. The electrons are supplied to the Cu—S bond. However, the method described in this proposal uses C
This is different from a method in which a p-type impurity and an n-type impurity which are not constituent elements of uInS ₂ are both doped into CuInS ₂ .

[0012]

However, as described above, a part of Cu, which is a constituent element of CuInS ₂ , is converted to I
When substituted by n, the donor vacancy In _Cu (in which the Cu site is substituted with In) is generated, and at the same time, in order to maintain charge neutrality in the vicinity thereof, Cu vacancy as an acceptor vacancy is generated. Occurs. Therefore, it is difficult to accurately control the amount of electrons supplied to the Cu—S bond by the amount of In replaced with Cu, and this method has manufacturing difficulties.

Further, in this method, since In is excessive, CuI having a chalcopyrite structure is contained in the CuInS ₂ layer.
CuIn ₅ S ₈ phase having a spinel structure different from nS ₂ is likely to be mixed. When phases having different crystal structures are mixed, many defects are likely to be generated particularly in the crystal grain boundaries of the CuInS ₂ layer. Moreover, the CuIn ₅ S ₈ phase has a high resistance. As a result, there is a problem that it is difficult to form p-type CuInS ₂ having a high carrier concentration.

The present invention has been made in view of the above-mentioned problems of the prior art, and is based on Ib-based materials such as CuInS _2.
Forming a p-type semiconductor having a high carrier concentration in the IIIb-VIb group ₂ compound semiconductor, which has higher performance and higher manufacturing advantages than the conventional method;
Another object is to realize a high-performance semiconductor device by using such a p-type semiconductor.

[0015]

In order to solve the above-mentioned problems, the present invention relates to a compound semiconductor of the group Ib-IIIb-VIb _II , in which a p-type impurity composed of a Vb group element and an n-type impurity composed of a IIb group element are added. And p-type semiconductors characterized by containing

The p-type semiconductor is a p-type semiconductor having a higher carrier concentration due to the presence of the n-type impurity than in the case where the same amount of p-type impurity is contained and no n-type impurity is present.

In the present invention, the p-type impurity means an acceptor impurity, and the n-type impurity means a donor impurity. The present invention also relates to Ib-II
Adding a p-type impurity composed of a Vb group element and an n-type impurity composed of a group IIb element to an Ib-VIb group ₂ compound semiconductor so that the content of the p-type impurity is higher than that of the n-type impurity. And a method for manufacturing a p-type semiconductor.

According to this method, a p-type semiconductor containing both a p-type impurity and an n-type impurity can be obtained. This p
By adding the n-type impurity together with the p-type impurity to the type semiconductor, the carrier concentration can be increased as compared with the case where only the p-type impurity is added in the same amount.

The p-type semiconductor obtained by adding both the p-type impurity and the n-type impurity to the Ib-IIIb-VIb group ₂ compound semiconductor has an increased p-type carrier concentration for the following reason. is there.

Element semiconductors such as Si and Ge are almost 100
% Covalent bond, whereas Ib-IIIb-VIb
The bond of the group _II compound semiconductor is a covalent bond having ionic bonding properties. Among them, CuInS ₂ is particularly CuInS ₂
in comparison with such as e ₂ is a strong ionic bond. The ionic bond tends to increase as the difference in electronegativity between the positive element and the negative element increases.

As described above, as the compound semiconductor has a stronger ionic bond, a negative element (an element on the electron receiving side) constituting the compound semiconductor is more easily removed when a p-type impurity is added. By adding the type impurities together, it is possible to prevent such omission of the negative element. As a result, the p-type carrier concentration becomes higher as compared with the case where both n-type impurities are not doped.

The p-type carrier concentration of the p-type semiconductor in which both the p-type impurity and the n-type impurity are contained in the Ib-IIIb-VIb group ₂ compound semiconductor is the difference between the p-type impurity content and the n-type impurity content. Will be a value corresponding to. When the ratio of the content of the p-type impurity to the content of the n-type impurity (which is larger than 1 for p-type) is small, both impurities must be used to increase the difference and obtain a high p-type carrier concentration. It is necessary to increase the content of, but if a large amount of impurities is contained, the crystallinity is reduced due to crystal distortion.

Therefore, the p-type semiconductor of the present invention has a high p-type
In order to obtain a mold carrier concentration, the ratio needs to be sufficiently large. The optimum value of this ratio varies depending on the required p-type carrier concentration and the type of impurity to be added, but the content of the p-type impurity is 1.3 to 3.0 times the content of the n-type impurity. Is preferred, and 1.8 to 2.
More preferably, it is twice.

When the content of the p-type impurity is at least 1.3 times the content of the n-type impurity, sufficient p-type conduction can be easily obtained as long as crystallinity is not deteriorated. Further, when the content of the p-type impurity exceeds 3.0 times the content of the n-type impurity, the effect of suppressing the removal of the negative element in the compound semiconductor by adding the n-type impurity becomes small, and the high p-type impurity is reduced. It becomes difficult to obtain a carrier concentration.

Next, the difference in operation between the method of the present invention and the conventional method will be described in detail, taking CuInS ₂ as an example of the Ib-IIIb-VIb ₂ group compound semiconductor. Cu
InS ₂ has InS bond and Cu-S bonds. In
In the -S bond, the total number of the three outermost shell electrons of In and the six outermost shell electrons of S is 9, which is one extra compared to eight of the stable bonds. In Cu-S bond, Cu 1
Since the total number of the outermost shell electrons and the six outermost shell electrons of S is seven, one is less than eight of the stable bonds.
One extra electron in the In-S bond is Cu-S
It is supplied to replenish electrons with insufficient bonding, and the entire system (base material) is stabilized.

However, V such as N which is a p-type impurity
When a group b element (the number of outermost electrons is 5) is added to replace S, the In—N bond becomes stable with the number of the outermost electrons being 8, but is supplied to the Cu—S bond. There are not enough electrons to be left.

Therefore, the Cu—S bond is in an unstable state as compared with the case where no p-type impurity is added. In such a state, Cu, which is likely to escape from the viewpoint of energy, escapes. When Cu escapes, adjacent S escapes or the added p-type impurity (N) escapes. Such escape of S or N is caused by the fact that S and N, which are electrically negative, are adjacent to each other due to the escape of Cu, and the Coulomb repulsion is increased.

A portion from which Cu has escaped (Cu vacancy) becomes an acceptor defect, and a portion from which S or N has escaped (S vacancy) becomes a donor defect. Then, since Cu is monovalent and S is divalent, if the same number of Cu and S are removed, the tendency of the donor property becomes stronger as a whole. Here, the added p-type impurity (acceptor impurity) is used to neutralize this strong donor property, so that a p-type carrier concentration corresponding to the doping amount of the p-type impurity cannot be obtained.

On the other hand, as in the method of the present invention, p
N-type impurities, IIb such as Zn
If the group element (2 outermost electrons) is added together, it replaces with Cu (1 outermost electron), leaving one extra electron, and the surplus electron becomes a Cu—S bond in the vicinity. , The above-mentioned Cu escape does not occur. As a result, the above-described strong donor state does not occur, and a p-type carrier concentration appropriate for the doping amount of the p-type impurity can be obtained.

It should be noted that electrons are effectively donated to the Cu-S bond which has become unstable due to the addition of the p-type
In order to stabilize the S bond, it is preferable that the n-type impurity exists near the p-type impurity in the base material (CuInS ₂ ).

In the method of the present invention, Ib-IIIb-
The p-type impurity added to the VIb group ₂ compound semiconductor may be any of Vb group elements, and the n-type impurity may be II
Any element may be used as long as it is a group b element, but a combination in which N is added as a p-type impurity and Zn and Cd are added alone or both as n-type impurities is preferable. Further, N is added as a p-type impurity, and Z is added as an n-type impurity.
Combinations in which n is added are particularly preferred.

The amount of carriers (holes) generated in a p-type semiconductor is determined by the content of a p-type impurity and its activation rate. When an impurity having a high activation rate is added, a high carrier density can be obtained with a small amount of addition, which is advantageous for increasing the carrier density. The activation rate is determined by the p formed in the forbidden band of the base material.
Depending on the depth of the type impurity level, the shallower the impurity level, the higher the activation rate. N has the shallowest impurity level among Vb group elements. That is, since N has the highest activation rate among Vb group elements, Ib-IIIb-V
Vb added as a p-type impurity to Ib group ₂ compound semiconductor
It is the most preferable element as a group element.

When N is added as a p-type impurity, the electronegativity of N is very large. Therefore, as an n-type impurity to be added together, the electronegativity of N with N is compared with Zn and Cd. It is preferable to use Zn having a larger difference. In this combination, since a large Coulomb attraction is generated between Zn and N, it is considered that usually unstable N can be stably present in the base material.

The Vb group element serving as a p-type impurity for CuInS ₂ has a valence other than -3 (for example, +3).
In this case, the Vb group element may be replaced with In without being replaced with S. In order to avoid this and replace the Vb group element with S to easily generate an acceptor, it is preferable to make the Vb group element more negative during doping. That is, the Vb group element is in the form of a compound with In (InP, InSb, etc.), in the form of a compound with Cu (Cu ₃ P, etc.), and further in the form of a compound with an alkali metal element (Li ₃ N, Na ₃ P, etc.)
It is preferable to supply with.

Further, it is known that adding an alkali metal element such as Na to the Ib-IIIb-VIb group ₂ compound semiconductor is effective for improving the conversion efficiency of a solar cell. A similar effect can be obtained by adding an alkali metal element together with the p-type impurity and the n-type impurity.

As described above, the method of the present invention provides the method of Ib-I
IIb-VIb Group ₂ compound semiconductor (for example, C
In the case of uInS ₂ , impurities other than Cu, In, and S)
In addition to the known method in which a part of Cu, which is a constituent element of CuInS ₂ , is replaced with In because of doping as a type impurity, an acceptor defect (p-type impurity) and a donor defect (n-type impurity) are added. The amount can be precisely controlled. Therefore, the method of the present invention is an effective method in terms of both ease of manufacturing and performance of the obtained p-type semiconductor.

In the method of the present invention, Ib-IIIb-
The timing of adding the p-type impurity and the n-type impurity to the VIb group ₂ compound semiconductor may be either simultaneous or different in terms of time, but if the p-type impurity is added before the n-type impurity, When a p-type impurity is added, a donor defect occurs due to the escape of the negative element as described above. Therefore, it is preferable to add the n-type impurity simultaneously with or before the p-type impurity.

In particular, when p-type impurities and n-type impurities are simultaneously added, both impurities are likely to be present in the vicinity of the base material and are also easily present uniformly in the whole base material. Become larger. In particular, a combination having a strong chemical bonding force between a p-type impurity and an n-type impurity (for example, N and Zn)
Etc.) is preferable because the tendency becomes remarkable.

The optimum method for forming a p-type semiconductor according to the present invention differs depending on the type and form of a compound semiconductor serving as a base material, such as a bulk or a thin film. All known methods can be used.

For example, in the case of a thin film, MBE or CV
By the method D, the element constituting the compound semiconductor as the base material and the p-type impurity and the n-type impurity may be simultaneously supplied to form the film, or the thin film of the compound semiconductor as the base material may be formed by the MBE method or the CVD method. Then, a p-type impurity and an n-type impurity may be added to the thin film by ion implantation or thermal diffusion. Since this method can obtain a high-quality film, it is generally and often used mainly as a method for forming a single crystal layer used for a light-emitting element or the like.

In addition, p, which is suitable as a constituent material of a solar cell,
As a method for producing the type CuInS ₂ film, there are a vacuum deposition method for simultaneously supplying constituent elements, a CuIn alloy thin film
/ In laminated film, furthermore, a CuInS alloy thin film or the like is formed, and then the thin film is heat-treated in an S-containing atmosphere.

In the case of the vacuum vapor deposition method, among the constituent elements, those which are solid at room temperature (for example, Zn, Sb, etc.) are usually formed into a molecular beam by heating a single element raw material in a K cell. Supply. When it is difficult to control the supply amount of a single element such as an element having a high vapor pressure (eg, P) which is solid at room temperature, Cu as a constituent element of the base material is used. Alternatively, the compound may be in the form of a compound with In or In or another doping element (solid raw material such as InP), and the compound may be supplied in a molecular beam by heating the compound in a K cell.

N is supplied in a gaseous state in the form of N ₂ in a vacuum. By activating this gas using a high-frequency coil as needed, the doping element can be easily taken into the CuInS ₂ thin film.

As the sulfurization method, C containing a doping element is used.
After forming a uIn (or CuInS) alloy thin film,
There is a method of heat-treating this alloy thin film in an atmosphere containing S. In this case, as a method of forming an alloy thin film containing a doping element, a method of simultaneously performing sputtering from a target of the doping element when forming the alloy thin film, first forming a film of the doping element, and then forming an alloy thin film thereon A method in which an alloy thin film is formed first, and a doping element is formed thereon to form a layer, and a doping element is added to an alloy (Cu, In, CuIn, CuInS, etc.). There is a method of forming a film by sputtering from a target. When N is used as the p-type impurity, N ₂ is used as the sputtering gas.
By mixing the gas, a CuIn (or CuInS) alloy thin film containing N can be formed.

In addition, when the CuIn (or CuInS) alloy thin film is sulfurized in an S-containing gas atmosphere, a gaseous doping element is supplied simultaneously with the S-containing gas to add the doping element to the alloy thin film. There is also.

As a method of forming p-type CuInS ₂ other than the vacuum deposition method and the sulfurization method, first, CuInS
₍₂₎ There is also a method of forming a thin film and adding a doping element therein by ion implantation. In this case, it is necessary to perform a heat treatment in order to improve the crystallinity reduced by the ion implantation. In order to prevent the occurrence of S loss during this heat treatment, it is preferable to perform the heat treatment in an S-containing gas atmosphere.

The present invention also relates to Ib-II as described above.
Provided is a semiconductor device including a p-type semiconductor containing a p-type impurity and an n-type impurity as a constituent material in an Ib-VIb group ₂ compound semiconductor.

[0048]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below using specific examples. Example 1 The same glass substrate was prepared, and a Mo film having a thickness of 1 μm was formed directly on one of the glass substrates and the other was formed thereon.
First, doping-free Cu
An InS ₂ film was formed.

That is, a CuInS film was formed by a reactive sputtering method using Cu and In as targets and a mixed gas of H ₂ S + Ar (H ₂ S concentration: 8%) as a sputtering gas. The substrate was not heated during this sputtering. Thereafter, the CuInS film is subjected to a heat treatment in an atmosphere of a H ₂ S + Ar mixed gas (H ₂ S concentration: 5%) at a temperature of 550 ° C.
_Two films were used.

Next, with respect to this CuInS ₂ film, Zn
(N-type impurity) and N (p-type impurity) were ion-implanted in the order of Zn and N. Thus, a CuInS ₂ film containing both a p-type impurity and an n-type impurity was obtained. The conditions for ion implantation are as follows. <Ion implantation conditions> Zn implantation energy: 10 (KeV), implantation amount: 5 × 10 ¹⁴ (c
m ⁻² ) N implantation energy: 10 (KeV), implantation amount: 1 × 10 ¹⁵ (c
m ⁻² ) CuInS ₂ whose crystallinity has been reduced by ion implantation.
CuInS after ion implantation to recrystallize the film
_{2 The} film was heated at a temperature of 520 ° C. in H ₂ S + Ar (H ₂ S concentration 5).
%).

When the thickness of the formed CuInS ₂ film was measured by a step gauge, it was 2.0 μm. The electrical characteristics of the CuInS ₂ film directly formed on a glass substrate
Inspection by Hall measurement using the der Pauw method revealed p-type conduction at a carrier concentration of 5 × 10 ¹⁷ (cm ⁻³ ).

The concentrations of N and Zn in the CuInS ₂ film were measured using a secondary ion mass spectrometer (IM, manufactured by Hitachi, Ltd.).
When measured using A-3), N was about 5 × 10
¹⁸ (cm ⁻³ ), Zn is about 2.5 × 10 ¹⁸ (cm ⁻³ )
Met.

On the glass substrate on which the CuInS ₂ film is formed via the Mo film, CuIn which is a p-type semiconductor layer is provided.
On the S ₂ film, C was formed as an n-type semiconductor layer by a solution growth method.
A dS film was formed with a thickness of 80 nm, and a transparent ITO (indium tin oxide) film was formed thereon as an electrode layer with a thickness of 0.8 μm by RF sputtering in order. Thereby, as shown in FIG. 1, a Mo film (electrode layer) 1, a CuInS ₂ film (p-type semiconductor layer) 3, a CdS film (n-type semiconductor layer) 4, and an ITO film (electrode) on a glass substrate 2. A thin-film solar cell having a layer structure having a layer 5 was produced.

The conversion efficiency of this solar cell was 12% when measured with a solar simulator (AM 1.5, 100 mW / cm ² ). Example 2 The same glass substrate was prepared, and a Mo film having a thickness of 1 μm was formed directly on one of the glass substrates and the other was formed on the other.
First, doping-free Cu
An InS ₂ film was formed.

That is, a CuInS film was formed by a reactive sputtering method using Cu and In as targets and using a mixed gas of H ₂ S + Ar (H ₂ S concentration: 8%) as a sputtering gas. The substrate was not heated during this sputtering. Thereafter, the CuInS film is subjected to a heat treatment in an atmosphere of a H ₂ S + Ar mixed gas (H ₂ S concentration: 5%) at a temperature of 550 ° C.
_Two films were used.

Next, Cd is applied to the CuInS ₂ film.
(N-type impurity) and N (p-type impurity) were ion-implanted in the order of Cd and N. Thus, a CuInS ₂ film containing both a p-type impurity and an n-type impurity was obtained. The conditions for ion implantation are as follows. <Ion implantation conditions> Cd implantation energy: 10 (KeV), implantation amount: 5 × 10 ¹⁴ (c
m ⁻² ) N implantation energy: 10 (KeV), implantation amount: 1 × 10 ¹⁵ (c
m ⁻² ) CuInS ₂ whose crystallinity has been reduced by ion implantation.
CuInS after ion implantation to recrystallize the film
_{2 The} film was heated at a temperature of 520 ° C. in H ₂ S + Ar (H ₂ S concentration 5).
%).

When the thickness of the formed CuInS ₂ film was measured by a step gauge, it was 2.0 μm. The electrical characteristics of the CuInS ₂ film directly formed on a glass substrate
Investigation by Hall measurement using the der Pauw method showed p-type conduction at a carrier concentration of 2 × 10 ¹⁷ (cm ⁻³ ).

When the concentrations of N and Cd in the CuInS ₂ film were measured in the same manner as in Example 1, N was about 5 × 10 ¹⁸ (cm ⁻³ ) and Cd was about 2.5 × 10
¹⁸ (cm ^-3 ).

On the glass substrate on which the CuInS ₂ film is formed via the Mo film, a CdS film and an ITO film are sequentially formed on the CuInS ₂ film in the same manner as in the first embodiment. A thin-film solar cell having a layer configuration as shown in FIG. 1 was produced.

The conversion efficiency of this solar cell was 11% when measured by a solar simulator (AM 1.5, 100 mW / cm ² ). [Comparative Example 1] The same glass substrate was prepared, and a Mo film having a thickness of 1 µm was formed directly on one of the glass substrates, and the other was formed on the other.
First, doping-free Cu
An InS ₂ film was formed.

That is, a CuInS film was formed on the Mo film by a reactive sputtering method using Cu and In as a target and a mixed gas of H ₂ S + Ar (H ₂ S concentration: 8%) as a sputtering gas. The substrate was not heated during this sputtering. Thereafter, the CuInS film was heat-treated in a H ₂ S + Ar mixed gas (H ₂ S concentration: 5%) atmosphere at a temperature of 550 ° C. to form a CuInS ₂ film.

Next, In and N are added to the CuInS ₂ film.
Was doped by ion implantation to form a CuInS ₂ film containing N (p-type impurity) as a doping element in CuInS ₂ in which a part of Cu was replaced by In. Ion implantation was performed in the order of In and N under the following conditions. <Ion implantation conditions> In implantation energy: 10 (KeV), implantation amount: 5 × 10 ¹⁴ (c
m ⁻² ) N implantation energy: 10 (KeV), implantation amount: 1 × 10 ¹⁵ (c
m ⁻² ) CuInS ₂ whose crystallinity has been reduced by ion implantation.
CuInS after ion implantation to recrystallize the film
_{2 The} film was heated at a temperature of 520 ° C. in H ₂ S + Ar (H ₂ S concentration 5).
%).

When the film thickness of the formed CuInS ₂ film was measured by a step gauge, it was 2.0 μm. The electrical characteristics of the CuInS ₂ film directly formed on a glass substrate
Inspection by Hall measurement using the der Pauw method showed p-type conduction at a carrier concentration of 2 × 10 ¹⁶ (cm ⁻³ ).

The concentration of N in the CuInS ₂ film was determined in Example 1.
It was measured in the same manner as approximately 5 × 10 ¹⁸ (cm
^-3 ). The concentration of In replaced with Cu could not be measured because In was a constituent element of the base material.

On the glass substrate on which the CuInS ₂ film was formed via the Mo film, a CdS film and an ITO film were sequentially formed on the CuInS ₂ film in the same manner as in the first embodiment. A thin-film solar cell having a layer configuration as shown in FIG. 1 was produced.

The conversion efficiency of this solar cell was 7% when measured by a solar simulator (AM 1.5, 100 mW / cm ² ). Comparative Example 2 A CuInS ₂ film was formed in the same manner as in Example 1, except that only the same amount of N (p-type impurity) was ion-implanted. When the electrical characteristics of this CuInS ₂ film were measured in the same manner as in Example 1, the carrier concentration was 1 × 10
^It exhibited a p-type conductivity of ¹⁵ (cm ^-3 ).

When the concentration of N in the CuInS ₂ film was measured in the same manner as in Example 1, it was about 5 × 10 ¹⁸ (c
m ^-3 ). This Cu only ion-implanted CuI
Example 1 except that the nS ₂ film was changed to the p-type semiconductor layer 3
In the same manner as described above, a thin-film solar cell having the layer configuration shown in FIG. 1 was produced. The conversion efficiency of this solar cell was 3% when measured by a solar simulator under the same conditions as in Example 1. Example 3 The same glass substrate was prepared, and a Mo film having a thickness of 1 μm was formed directly on one of the glass substrates and on the other,
N (p-type impurity) and Zn (n
A CuInS ₂ film containing a (type impurity element) was formed as follows.

First, a CuIn film containing N and Zn was formed on the glass substrate and the Mo film, respectively.
This CuIn film includes an In target, a Cu target,
N ₂ + Ar mixed gas (N
₍₂ concentration 5%) It was formed by performing simultaneous sputtering in a gas atmosphere. In addition, the substrate was not heated during the sputtering. Next, the CuInS film containing N and Zn was heat-treated at a temperature of 550 ° C. in an H ₂ S + Ar mixed gas (H ₂ S concentration: 5%) atmosphere to form a CuInS ₂ film containing N and Zn. .

When the thickness of the formed CuInS ₂ film was measured with a step gauge, it was 2.0 μm. The electrical characteristics of the CuInS ₂ film directly formed on the glass substrate
Hall measurement using the nder Pauw method showed p-type conduction at a carrier concentration of 5 × 10 ¹⁷ (cm ⁻³ ).

When the concentrations of N and Zn in the CuInS ₂ film were measured in the same manner as in Example 1, it was found that N was about 5 ×
10 ¹⁸ (cm ⁻³ ), Zn is approximately 2.5 × 10 ¹⁸ (cm
^-3 ).

On a glass substrate on which a CuInS ₂ film is formed via a Mo film, a CdS film and an ITO film are sequentially formed on the CuInS ₂ film in the same manner as in the first embodiment. A thin-film solar cell having a layer configuration as shown in FIG. 1 was produced.

The conversion efficiency of this solar cell was 13% when measured by a solar simulator (AM 1.5, 100 mW / cm ² ). Example 4 The same glass substrate was prepared, a Mo film having a thickness of 1 μm was formed directly on one of the glass substrates, and the other was formed on the other.
Except that a CuIn film containing N and Zn was formed so that the Zn concentration was about two-fifths of Example 3,
N (p-type impurity) and Z
A CuInS ₂ film containing n (n-type impurity element) was formed.

The thickness of the formed CuInS ₂ film was 2.0 μm as measured by a step gauge. The electrical characteristics of the CuInS ₂ film directly formed on the glass substrate
Hall measurement using the nder Pauw method showed p-type conduction at a carrier concentration of 8 × 10 ¹⁶ (cm ⁻³ ).

The concentrations of N and Zn in the CuInS ₂ film were measured in the same manner as in Example 1.
10 ¹⁸ (cm ⁻³ ), Zn is about 1 × 10 ¹⁸ (cm ⁻³ )
Met.

On the glass substrate on which the CuInS ₂ film is formed via the Mo film, a CdS film and an ITO film are sequentially formed on the CuInS ₂ film in the same manner as in the first embodiment. A thin-film solar cell having a layer configuration as shown in FIG. 1 was produced.

The conversion efficiency of this solar cell was 10% as measured by a solar simulator (AM 1.5, 100 mW / cm ² ). In Example 4, the content of the p-type impurity was 5.0 times the content of the n-type impurity,
"The content of the p-type impurity is 1.3 to less than the content of the n-type impurity.
3.0 times ", the carrier concentration and the conversion efficiency are slightly smaller than those in Examples 1 and 3 which are 2.0 times. Example 5 The same glass substrate was prepared, a Mo film having a thickness of 1 μm was formed directly on one of the glass substrates, and the other was formed on the other.
P (p-type impurity) and Zn (n
A CuInS ₂ film containing a (type impurity element) was formed as follows.

First, a CuIn film containing P and Zn was formed on the glass substrate and the Mo film, respectively.
This CuIn film includes a Cu target, a Zn target,
And an InP target loaded with InP pellets,
It was formed by performing simultaneous sputtering in an Ar gas atmosphere. During the sputtering, the substrate was not heated. Next, the CuInS film containing P and Zn is heat-treated at a temperature of 550 ° C. in an H ₂ S + Ar mixed gas (H ₂ S concentration: 5%) atmosphere.
A CuInS ₂ film containing P and Zn was used.

When the thickness of the formed CuInS ₂ film was measured by a step gauge, it was 2.0 μm. The electrical characteristics of the CuInS ₂ film directly formed on the glass substrate
Hall measurement using the nder Pauw method showed p-type conduction at a carrier concentration of 1 × 10 ¹⁷ (cm ⁻³ ).

When the concentrations of P and Zn in the CuInS ₂ film were measured in the same manner as in Example 1, it was found that P was about 5 ×
10 ¹⁸ (cm ⁻³ ), Zn is approximately 2.5 × 10 ¹⁸ (cm
^-3 ).

On the glass substrate on which the CuInS ₂ film is formed via the Mo film, a CdS film and an ITO film are sequentially formed on the CuInS ₂ film in the same manner as in the first embodiment. A thin-film solar cell having a layer configuration as shown in FIG. 1 was produced.

The conversion efficiency of this solar cell was 10% as measured by a solar simulator (AM 1.5, 100 mW / cm ² ). Comparative Example 3 A CuInS ₂ film was formed in the same manner as in Example 5, except that only the same amount of P (p-type impurity) was doped.

When the electrical characteristics of the CuInS ₂ film were measured in the same manner as in Example 1, the carrier concentration was 3 × 10
^It exhibited a p-type conductivity of ¹⁵ (cm ^-3 ). When the concentration of P in the CuInS ₂ film was measured in the same manner as in Example 1, it was about 5 × 10 ¹⁸ (cm ⁻³ ).

CuInS in which only P is ion-implanted
A thin-film solar cell having the layer configuration shown in FIG. 1 was produced in the same manner as in Example 1 except that the _two films were changed to the p-type semiconductor layer 3. The conversion efficiency of this solar cell was measured using a solar simulator under the same conditions as in Example 1, and was 4%.

[0084]

As described above, the p-type semiconductor of the present invention has a p-type semiconductor due to the presence of the n-type impurity added to the Ib-IIIb-VIb group ₂ compound semiconductor together with the p-type impurity.
The type carrier concentration has a value commensurate with the content of the p-type impurity. Further, a high-performance semiconductor device is realized by the p-type semiconductor.

According to the p-type semiconductor manufacturing method of the present invention,
By adding an n-type impurity together with a p-type impurity to the Ib-IIIb-VIb group ₂ compound semiconductor, a p-type semiconductor having a high carrier concentration commensurate with the content of the p-type impurity can be obtained.

According to this method, the amounts of the p-type impurity and the n-type impurity can be precisely controlled. Therefore, a known method for substituting the constituent elements of the Ib-IIIb-VIb group ₂ compound semiconductors is used. Rather, the carrier concentration as set can be easily realized.

Further, the method of the present invention relates to the method of Ib-IIIb-
Particularly high effects can be obtained when the present invention is applied to CuInS ₂ having a particularly strong ionic bond among the VIb ₂ group compound semiconductors.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a layer configuration of a thin-film solar cell formed in an embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 1 Mo film (electrode layer) 2 glass substrate 3 CuInS ₂ film (p-type semiconductor layer) 4 CdS film (n-type semiconductor layer) 5 ITO film (electrode layer)

Claims (10)

[Claims] 1. A p-type semiconductor comprising: a group Ib-IIIb-VIb group ₂ compound semiconductor containing a p-type impurity comprising a group Vb element and an n-type impurity comprising a group IIb element. 2. The p-type impurity is N and the n-type impurity is Z
The p-type semiconductor according to claim 1, wherein n is n. 3. The method according to claim 1, wherein the content of the p-type impurity is 1.3 to 3.0 times the content of the n-type impurity.
Or the p-type semiconductor according to 2. 4. A Ib-IIIb-VIb ₂ group compound semiconductor is characterized in that it is a CuInS ₂ claims 1 to 3
The p-type semiconductor according to any one of the above. 5. A p-type impurity composed of a Vb group element and IIb-IIIb-VIb group _II compound semiconductor,
A method for producing a p-type semiconductor, characterized by adding an n-type impurity comprising a group element so as to have a higher p-type impurity content than an n-type impurity. 6. The p-type semiconductor manufacturing method according to claim 5, wherein the n-type impurity is added to the compound semiconductor simultaneously with or before the p-type impurity. 7. The method for manufacturing a p-type semiconductor according to claim 5, wherein N is added as a p-type impurity and Zn is added as an n-type impurity. 8. The method according to claim 5, wherein both impurities are added such that the content of the p-type impurity is 1.3 to 3.0 times the content of the n-type impurity. 5. A method for manufacturing a p-type semiconductor according to any one of the above. 9. Claim Ib-IIIb-VIb ₂ group compound semiconductor is characterized in that it is a CuInS ₂ 5 to 8
The method for producing a p-type semiconductor according to any one of the above. 10. A p-type semiconductor according to any one of claims 1 to 4 or a p-type semiconductor produced by the method according to any one of claims 5 to 9 as a constituent material. A semiconductor device.