JPH0334673B2 - - Google Patents

Description

Detailed Description of the Invention The present invention provides a first semiconductor layered body having a first conductivity type, and a first conductivity type disposed on the first semiconductor layered body via a PN junction. a second semiconductor layered body having an opposite second conductivity type.
Concerning improvements in PN junction devices.

As shown in FIG. 1, such a type of PN junction element conventionally includes, for example, an N-type first semiconductor layered body 1 and a P-type second semiconductor layered body disposed on the semiconductor layered body 1 via a PN junction 2. a semiconductor layer 3, in which case the semiconductor layer 1 consists of a semiconductor substrate 4 having a relatively low resistivity, thus designated "N ⁺ ";
In addition, the semiconductor layered body 3 has a relatively high resistivity on the semiconductor layered body 1 side, that is, on the semiconductor substrate 4. Therefore, the first semiconductor layer 5, which is represented by "P ^- ", and the comparison on the semiconductor layer 5. a second semiconductor layer 6, which has a low resistivity and is therefore denoted “P ⁺ ”;
The semiconductor substrate 4 and all of the semiconductor layers 5 and 6, and therefore all of the semiconductor layered bodies 1 and 3, are made of single crystal silicon, while the semiconductor layered body 1 and therefore the semiconductor substrate 4 are placed on the side opposite to the semiconductor layered body 3 side. A configuration was proposed in which an electrode 7 is attached to an ohmic, and an electrode 8 is attached to an ohmic on the semiconductor layer 6 constituting the semiconductor layered body 3 on the side opposite to the semiconductor layered body 1. ing.

It is clear that the PN junction element having such a configuration functions as a PN junction diode, but in this case, the semiconductor layered body 1 is a semiconductor substrate 4 having a relatively low resistivity, and the semiconductor substrate 4 Since the electrode 7 is attached to the semiconductor layered body 3, the electrode 7 is connected to the semiconductor layered body 1 with good ohmic contact.
has a semiconductor layer 6 having a relatively low resistivity,
Since the electrode 8 is attached to the semiconductor layer 6, the electrode 8 is connected to the semiconductor layered body 3 with good ohmic contact, and therefore functions as a PN junction diode in this respect. It has the characteristic of exhibiting good properties.

Further, in the PN junction element having the configuration described above in FIG. 1, the semiconductor layered body 3 has a semiconductor layer 5 having a relatively high resistivity, and the semiconductor layer 5
is inserted between the semiconductor substrate 4 and the semiconductor layer 6, which have relatively low resistivity, so that the electrodes 7 and 8
It has a high pressure resistance, and is therefore easy to use.

However, the PN having the configuration described above in FIG.
In the case of a junction element, the semiconductor layer 6 having a relatively low resistivity constituting the semiconductor layer 3 is also made of single crystal silicon together with the other semiconductor layers 5 and the semiconductor layer 1. A semiconductor substrate 4 made of crystalline silicon is prepared in advance, and a P-type single crystal silicon layer having a relatively high resistivity is formed on the semiconductor substrate 4 by an epitaxial growth method. P-type impurities are introduced from the surface side to a depth that does not reach the semiconductor substrate 4 by thermal diffusion or ion implantation, and the region of the single crystal silicon layer into which the P-type impurities are introduced becomes a semiconductor. It is generally obtained by obtaining the layer 6 and the unintroduced region as the semiconductor layer 5. However, when the semiconductor layer 6 is obtained by the thermal diffusion method, a processing temperature of 900° C. or higher is usually required, and when the semiconductor layer 6 is obtained by the ion implantation method, the activation of the impurity to be implanted and the impurity implantation are performed. Therefore, treatment at a temperature of 900° C. or higher is required to remove crystal defects generated in the single crystal silicon layer, and therefore, high temperature treatment is required to obtain the semiconductor layer 6.

Therefore, in the case of the conventional PN junction element shown in FIG. 1, the semiconductor layered bodies 1 and 3 are obtained with crystal defects and are contaminated with unnecessary impurities. At this point, PN
It has the disadvantage that it does not function well as a junction diode.

In addition, in the case of the conventional PN junction element described above in FIG. 1, if a bias source is connected between the electrodes 7 and 8 with a polarity that biases the PN junction 2 in the forward direction, as shown in FIG. It has an energy band structure as shown, and electrons 10 are released from the semiconductor layered body 1.
crosses the PN junction 2 and enters the semiconductor layered body 3;
The mechanism is such that the current flows through the electrodes 7 and 8, and the current reaches the electrode 8, but the semiconductor layer 5
and 6 are both made of single crystal silicon, and since the semiconductor layer 6 has a lower resistivity than the semiconductor layer 5, there is a barrier 11 for the electrons 10 at the interface between the semiconductor layers 5 and 6. A part of the flow of electrons 10 from the body 1 side toward the electrode 8 side is blocked by the barrier 11, thus creating a relatively large forward voltage drop between the electrodes 7 and 8, and causing electrons to flow into the semiconductor layer 5. A relatively large amount will be accumulated.

Therefore, the conventional PN junction element described above in FIG. 1 has the disadvantage that it only functions as a PN junction element with large power consumption and only at low speed.

Conventionally, as shown in FIG. 3, as in the case of FIG. a second semiconductor layer 3 of which, however, in this case the semiconductor layer 1 has a relatively low resistivity, thus designated as "N ⁺ ", and a comparative The semiconductor layer 5 has a relatively high resistivity and is therefore designated as "N ^- ", and the semiconductor layer 3 has a relatively low resistivity and therefore has a semiconductor layer 6 that is designated as "P ⁺ ". Then, the semiconductor substrate 4 and all the semiconductor layers 5' and 6, and therefore all the semiconductor layered bodies 1 and 3, are made of single crystal silicon as in the case of FIG. 4
Another structure has also been proposed in which an electrode 7 is attached to the semiconductor layer 6 as in the case of FIG. 1, and an electrode 8 is attached to the semiconductor layer 6 as the semiconductor layered body 3 as in the case of FIG.

The PN junction element having such a configuration also functions as a PN junction diode, as in the case of FIG. 1, and also has a semiconductor substrate 4 having a relatively low resistivity.
Since the electrodes 7 and 8 are attached to the semiconductor layer 6, the electrodes 7 and 8 are attached to the semiconductor substrate 4, respectively.
and the semiconductor layer 6 through good ohmic contact, and therefore has the characteristic of exhibiting a good function as a PN junction diode in this respect.

Also, in the PN junction element having the configuration described above in FIG. It has the characteristics of high pressure resistance and therefore ease of use.

However, the PN having the configuration described above in FIG.
In the case of a junction element, as in the case of FIG. 1, the semiconductor layer 6 having relatively low resistivity is also made of single crystal silicon together with the other semiconductor layer 5' and the semiconductor layered body 1. It is necessary to perform high-temperature treatment to obtain the semiconductor layered body 1 as in the case of FIG.
and 3 were obtained with crystal defects and were contaminated with unnecessary impurities, and in this respect, they had the disadvantage that they did not function well as a PN junction diode. .

Therefore, the present invention provides a novel PN without the above-mentioned drawbacks.
This will become clear from the detailed description below.

FIG. 4 shows an example of a PN junction element according to the present invention. Parts corresponding to those in FIG. 1 are given the same reference numerals and detailed explanation thereof is omitted. The semiconductor layer 6 made of P-type single crystal silicon having a relatively low resistivity and constituting the semiconductor layered body 3 is amorphous silicon having a P-type relatively low resistivity or silicon and a semiconductor layer 6 made of amorphous silicon having a relatively low resistivity. It has the same structure as the case of FIG. 1 except that it is replaced with a semiconductor layer 16 made of a multi-component amorphous semiconductor made of elements. However, in this case, the semiconductor layer 16 contains boron as a P-type impurity at a high concentration. In the case where the semiconductor layer 16 is made of an amorphous semiconductor consisting of silicon and a group element other than silicon, the group element may include germanium, tin, etc., which have a larger atomic radius than silicon, and particularly germanium. It is something.

The above is an example of the configuration of the PN junction element according to the present invention, and it is clear that with such a configuration it functions as a PN junction diode as in the case of FIG. The electrodes 7 and 8 are ohmicly attached to the semiconductor substrate 4 having a relatively low resistivity and the semiconductor layer 16 having a relatively low resistivity constituting the semiconductor layered body 3, respectively. are connected to the semiconductor substrate 4 and the semiconductor layer 16, respectively, with good ohmic contact, and therefore, in this respect, as in the case of FIG. 1, it functions well as a PN junction diode. It has the following characteristics.

Further, according to the structure of the PN junction element according to the present invention described above in FIG. 4, the semiconductor layered body 3 is
As in the case of FIG. 1, since the semiconductor layer 5 has a relatively high resistivity, as in the case of FIG.
It has a high withstand voltage between the electrodes 7 and 8, and is therefore convenient to use.

However, the PN according to the present invention described above in FIG.
According to the configuration of the bonding element, the semiconductor layer 16 having a relatively low resistivity, which constitutes the semiconductor layered body 3,
Unlike other semiconductor layers 5 and the semiconductor layered body 1 made of single crystal silicon, the semiconductor layered body 1 is made of amorphous silicon or a multi-dimensional amorphous semiconductor composed of silicon and a group element other than silicon. A semiconductor substrate 4 is prepared in advance, a semiconductor layer 5 is formed on the semiconductor substrate 4 by an epitaxial growth method, and a semiconductor layer 5 is formed on the semiconductor layer 5 by a vapor deposition method, a sputtering method, a glow discharge method, a CVD method, etc. This can be obtained by a method in which the semiconductor layer 16 is formed using the following method. However, when the semiconductor layer 16 is obtained by a vapor deposition method, a sputtering method, or a glow discharge method, the temperature of the semiconductor substrate 4 may be about 300° C. to 400° C. or lower, and the semiconductor layer 16 may be obtained by a CVD method. In this case, the temperature of the semiconductor substrate 4 may be about 600° C. or lower, and therefore, in order to obtain the semiconductor layer 16, high-temperature treatment is required as in the case of obtaining the semiconductor layer 6 in the case of FIG. It's something you don't do.

Therefore, according to the configuration of the PN junction element according to the present invention as described above in FIG. It is not obtained as contaminated with accompanying or unnecessary impurities,
Therefore, in this respect, it has a feature that it functions as a PN junction diode better than the conventional PN junction element described above in FIG. 1.

Further, according to the configuration of the PN junction element according to the present invention described above in FIG. As in the case of FIG. 1, electrons from the semiconductor layered body 1 cross the PN junction 2, enter the semiconductor layered body 3, and reach the electrode 8, which causes a current to flow through the electrodes 7 and 8. However, among the semiconductor layers 5 and 16 constituting the semiconductor layered body 3, the former semiconductor layer 5 is made of single crystal silicon, but the latter semiconductor layer 16 is made of amorphous silicon or silicon and a group element other than silicon. It is a multidimensional amorphous semiconductor,
In addition, by containing boron as a P-type impurity at a high concentration, the interface between the semiconductor layers 5 and 16 has
It does not have a barrier such as the barrier 11 at the interface between the semiconductor layers 5 and 6 of the conventional PN junction element described above in FIG. It is much smaller than the conventional PN junction element described above in the figure, and electrons are not accumulated in the semiconductor layer 5 in large numbers as in the case of the PN junction element shown in FIG.

Incidentally, the semiconductor substrate 4 as the semiconductor layered body 1 is an N-type single crystal silicon substrate with a resistivity of 0.01 Ωcm, and the semiconductor layer 5 forming the semiconductor layered body 3 has a resistivity of 0.01Ωcm and is formed by an epitaxial growth method.
The semiconductor layer 16 is made of silicon and germanium and contains boron as a P-type impurity, and has a resistivity of 1.6 Ωcm. P
When the forward voltage current characteristics were measured in the case where the electrodes 7 and 8 were made of metal electrodes made of aluminum and nickel, the results shown by the solid line in FIG. 5 were obtained. Ta. On the other hand, in the conventional PN junction element described above in FIG. When 7 and 8 are the metal electrodes mentioned above, and the semiconductor layer 6 is a single crystal silicon layer containing boron as a P-type impurity with a surface concentration of 5×10 ¹⁸ cm ^-3 and a thickness of 1 μm, the forward voltage-current characteristics When measured, the results shown by the dotted line in FIG. 5 were obtained. Furthermore, the results obtained in the conventional PN junction element shown in FIG. 1 were also the same when the semiconductor layer 6 was a polycrystalline silicon layer containing boron as a P-type impurity at a high concentration. Even above this, in the case of the PN junction element according to the present invention, the first
It is clear from the figure that the forward voltage drop is much smaller than in the case of the conventional PN junction element described above.

Further, in the PN junction element according to the present invention described above in FIG. 4, the semiconductor layered body 1 and the semiconductor substrate 4,
semiconductor layers 5 and 16 that constitute the semiconductor layered body 3;
Electrodes 7 and 8 were connected in the same way as in the case where the measurement results shown by the solid line in ^FIG .
When the reverse current with respect to time was measured when the polarity of the power source was reversed, the results shown by the solid line in FIG. 6 were obtained. On the other hand, in the conventional PN junction element described above in FIG. Similarly,
When the reverse current was measured over time in the same manner as described above, the results shown by the dotted line in FIG. 6 were obtained.
From this, it is clear that in the case of the PN junction element according to the present invention, the amount of electrons accumulated in the semiconductor layer 5 is much smaller than in the case of the conventional PN junction element shown in FIG. Will.

Therefore, in the case of the PN junction element according to the present invention shown in FIG. 4, the function as a PN junction diode can be achieved with significantly lower power consumption than in the case of the conventional PN junction element shown in FIG. It has the great feature that it can operate at a much higher speed than the conventional PN junction element.

Further, the feature of the present invention described above is that in the configuration shown in FIG. Even more so if it is smaller. The reason is that when the semiconductor layer 5 has such a thickness,
As mentioned above, when electrons flow from the semiconductor layered body 1 side to the electrode 8 side, the electrons easily cross the semiconductor layer 5 as minority carriers and enter the semiconductor layer 16. This is because it is effectively absorbed.

Furthermore, the present inventors have discovered that the above-mentioned effects of the present invention are more pronounced as the density of levels in the mobility gap of the amorphous semiconductor increases. In other words, if expressed in terms of the optical absorption coefficient for light with energy lower than the energy equivalent to the optical band gap, for example, even for light with a photon energy of 0.5 eV, the optical absorption coefficient is as large as not less than 10 ³ cm ^-1. Amorphous silicon or a multi-component amorphous semiconductor containing silicon is preferred. Incidentally, since the light absorption coefficient of the above-described multi-component amorphous semiconductor made of P-type silicon and germanium is as shown in FIG. 7, this condition is satisfied. In particular, from the viewpoint of high level density in the gap, amorphous silicon containing impurities produced by CVD, sputtering, or vapor deposition, or a multi-component amorphous semiconductor made of silicon and a group element other than silicon is preferable.

In addition, amorphous silicon or a multi-component amorphous semiconductor composed of silicon and a group element other than silicon can contain acceptor impurities or donor impurities that have a solubility higher than that in single crystal silicon. As a result of the experiments conducted by the present inventors, it has become clear that the above-mentioned effect can be made more significant by using a compound that has a lower temperature.

Furthermore, in the case of the above-mentioned PN junction element according to the present invention, the semiconductor layer 16 constituting the semiconductor layered body 3
Since it is amorphous silicon or the multi-component amorphous semiconductor mentioned above, an impurity made of boron that makes it P-type is added to the semiconductor layer 16.
It can be contained in a larger amount than the solubility in single crystal silicon. For this reason, the series resistance seen between the electrodes 7 and 8 in the semiconductor layer 16 is sufficiently reduced, and the effect of accumulating electrons in the semiconductor layer 5 is sufficiently reduced, so that the above-described features of the present invention are more fully exhibited. It is obtained by doing.

Next, another example of the PN junction element according to the present invention will be described with reference to FIG. 8. Parts corresponding to those in FIG.
In the configuration described above in FIG. 1, the semiconductor layer 6 made of single crystal silicon as the semiconductor layered body 3 is
However, as in the case of the PN junction element according to the present invention described above in FIG. It has the same structure as the case of FIG. 3, except that it is replaced with a semiconductor layer 16 containing boron as a P-type impurity at a high concentration. In this example, when the semiconductor layer 16 is made of a multi-component amorphous semiconductor consisting of silicon and a group element other than silicon, the group element may include germanium, tin, etc., as described above in FIG. It is compatible with germanium.

The above is the configuration of another example of the PN junction element according to the present invention, and it is clear that according to such a configuration, it functions as a PN junction diode similarly to the case of FIG. Since the electrodes 7 and 8 are attached to the semiconductor substrate 4 and the semiconductor layer 16, respectively, which have low resistivity, the electrodes 7 and 8 are connected to the semiconductor substrate 4 and the semiconductor layer 16, respectively, with good ohmic contact. Therefore, in this respect, it is characterized in that it functions well as a PN junction diode, similar to the case shown in FIG.

Further, according to the configuration of the PN junction element according to the present invention as described above in FIG. Similar to the case shown in FIG. 3, this device has a high withstand voltage between the electrodes 7 and 8, and is therefore convenient to use.

However, the PN according to the present invention described above in FIG.
According to the structure of the junction element, the semiconductor layer 16 as the semiconductor layered body 3 is made of amorphous silicon or silicon and a group element other than silicon, as in the case of the PN junction element according to the present invention described above in FIG. Since the semiconductor layered body 1 is a multi-component amorphous semiconductor, a detailed explanation thereof will be omitted, but it is possible to obtain a semiconductor layered body 1 with crystal defects or contaminated with unnecessary impurities as in the case of FIG. Therefore, in this respect, it is characterized in that it functions as a PN junction diode better than the conventional PN junction element shown in FIG. 3 above.

Further, according to the structure of the PN junction element according to the present invention described above in FIG. The electrodes 7 and 8 are made of a multi-component amorphous semiconductor consisting of the elements 7 and 8, and contain a high concentration of boron as a P-type impurity.
The forward voltage drop generated between the two is much smaller than that of the conventional PN junction element shown in FIG. It is something that does not accumulate in large quantities. Incidentally, the semiconductor substrate 4 is an N-type single crystal silicon substrate with a resistivity of 0.01 Ωcm, and the semiconductor layer 5'
is an N-type single crystal silicon layer with a resistivity of 5 Ωcm and a thickness of 17 μm formed by an epitaxial growth method, and the semiconductor layer 16 is formed by a CVD method and is made of silicon and germanium and contains boron. P containing as a P-type impurity and having a resistivity of 1.6Ωcm
When the forward voltage and current characteristics were measured in the case where the electrodes 7 and 8 were metal electrodes made of aluminum and nickel, the results shown by the solid line in FIG. 9 were obtained. Ta. On the other hand, in the conventional PN junction element shown in FIG. However, the semiconductor layer 6 has a surface concentration of 5×10 ¹⁸ cm
^-3 , a single crystal silicon layer containing boron as a P-type impurity and having a thickness of 1 μm was measured for forward voltage-current characteristics, and the results shown by the dotted line in FIG. 9 were obtained. Further, the results obtained in the conventional PN junction element shown in FIG. 3 were also obtained when the semiconductor layer 6 was a polycrystalline silicon layer containing boron as a P-type impurity at a high concentration. Even more than this, in the case of the PN junction element according to the present invention, the conventional PN junction element shown in FIG.
It is clear that the forward voltage drop is much smaller than that of a junction element. In the case of this example as well, in comparison with the case of the conventional PN junction element shown in Fig. 3, the same reverse current as described above in Fig. 6 was measured according to the method described above in Fig. 4. However, in FIG. 6, results similar to those described above were obtained. Therefore, the amount of electrons accumulated in the semiconductor layer 5' is smaller than that of the conventional PN shown in FIG.
It has become clear that the size is significantly smaller than that of a bonding element.

Therefore, in the case of the PN junction element according to the present invention shown in FIG. 8, the function as a PN junction diode can be performed with much lower power consumption than in the case of the conventional PN junction element shown in FIG. It has the great feature of being able to display the data as if it were not present, and at a much higher speed.

Further, such characteristics include the thickness of the semiconductor layer 5', the material of the multi-component amorphous semiconductor when the semiconductor layer 16 is made of a multi-component amorphous semiconductor, etc.
Although the detailed explanation is omitted, it can be obtained more effectively by using the same method as described above with reference to FIG. 4.

In the above, the present invention was applied to a PN junction diode, but it can also be applied to a PNP type or NPN
It will be obvious that the present invention can be applied to any element having a PN junction, even if it is a type of transistor.

[Brief explanation of drawings]

1 and 3 are cross-sectional views showing a conventional PN junction element, FIG. 2 is an energy band structure diagram, FIGS. 4 and 8 are sectional views showing an example of a PN junction element according to the present invention, and FIG. 9 and 9 are forward voltage current characteristic diagrams, FIG. 6 is a reverse current characteristic diagram, and FIG. 7 is a diagram showing light absorption of a semiconductor layer.

Claims (1)

[Claims] 1. A first semiconductor layered body having an N type, and a second semiconductor layered body having a P type disposed on the first semiconductor layered body via a PN junction. In the PN junction element, the first semiconductor layered body is composed of a single crystal silicon substrate having a relatively low resistivity, and a single crystal silicon layer having a relatively high resistivity on the single crystal silicon substrate, and the above-mentioned A PN junction element characterized in that the second semiconductor layered body is made of amorphous silicon or a multi-component amorphous semiconductor consisting of silicon and a group element other than silicon, and contains boron as a P-type impurity at a high concentration. . 2. In a PN junction element comprising a first semiconductor layered body having N type and a second semiconductor layered body having P type disposed on the first semiconductor layered body via a PN junction. , the first semiconductor layered body is made of single crystal silicon, and the second semiconductor layered body includes a first semiconductor layer having a relatively high resistivity on the side of the first semiconductor layered body, and a first semiconductor layer having a relatively high resistivity on the first semiconductor layered body side; a second semiconductor layer having a relatively low resistivity on the semiconductor layer; the first semiconductor layer is made of single crystal silicon; and the second semiconductor layer is made of amorphous silicon or a group other than silicon and silicon. It is characterized by being a multi-component amorphous semiconductor consisting of the elements and containing a high concentration of boron as a P-type impurity.
PN junction element.