JPS59132657A - Photoelectric conversion device - Google Patents

Abstract

PURPOSE:To enable the use of a sensitivity layer of a low specific resistance and contrive to improve the transverse directional isolation by providing a plurality of signal sampling electrodes or regions and a photoelectric conversion layer joining thereto and having a selective impurity barrier region. CONSTITUTION:The signal sampling electrodes or regions 8 are selectively arranged on a substrate 7 of semiconductor, etc., and an N type layer 9, an I type layer, and a P type layer 11 composed of amorphous Si are deposited by silan gas, etc. and addition gas. Further, an implanted region 15 is formed by selective ion implantation, e.g., by implanting a P type impurity such as boron B. Next, a clear electrode 12 of an ITO and the like is laminted. It is also available that this implanted substance is a high resistant substance such as oxygen, nitrogen, or carbon. For the formation of this implanted region 15, there is a method such as thermal dispersion by a film source containing impurities. A negative voltage is impressed on the clear electrode 12, and a positive voltage on the sampling electrodes or regions 8, and an electric field E is drawn in the positive direction to electrons.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a photoelectric conversion device having a photoelectric conversion layer.

Structures of conventional examples and their problems In recent years, since W, E 5pear et al. showed in 1976 that it was possible to control charge electrons in amorphous silicon, that is, form P-type and n-type semiconductor layers, non-single-crystal materials have been developed. Basic and applied research on crystalline (amorphous) silicon has become active. It goes without saying that research into solar cells with a p-1-n diode structure is active as part of applied research, but rather than using the current generated by this light as energy, it is important to apply it to photoelectric conversion sensors. Research has also begun.

In general, amorphous silicon is often manufactured by the method of releasing silane (SiH4) gas by the method of η1:min i++ (Fig. The photoelectric conversion sensor also has essentially a similar structure.In Fig. 1,
1 is a glass or metal substrate, 2 is diborancus (B2)
! 6) n-type amorphous silicon J'l added with etc.
'i (nI so), 3 is an intrinsic amorphous silicon j so (iFJ) to which no impurity gas is added. Of course, a trace amount of impurity gas may be added to each layer 3. 4 is a p-type amorphous silicon layer (1) to which impurity gas such as Honufin (PH3) is added, 5 is a metal electrode (At, Au, etc.) or transparent type I'1l (ITo).
). Light is incident from the substrate 1 or from the side of the substrate 1. Figure b shows the pant model of figure a, and the incidence of light generates a carrier pattern 16 of electrons and holes, and the electrons are transferred to the substrate 1 side. What diffuses toward the electrode 5 becomes a current and is taken out to the outside.

The greater the number of carriers that reach both sides due to this diffusion, the greater the amount of current that can be extracted to the outside. That is, the smaller the resistivity of this single layer 3 and the longer the diffusion length, the better. In normal decomposition of silanganu, the resistivity is about 10Ω0m. On the other hand, when used as a sensor film, this sensitive layer 1
If the resistivity of the layer 3 is not as large as 10 to 10 Ω1- (near n layer 19), the signal will be diffused in the lateral direction, and the signal-to-signal characteristics will be poor.

Figure 2 shows an example of a sensor with a structure similar to that of a solar cell, and Figure a shows a scanning circuit (
A signal sampling link electrode or region 8 is arranged which is electrically scanned by a signal sampling link electrode (not shown), and an n-type amorphous silicon layer (n layer) 9 is formed as a photoelectric conversion layer thereon. (1AQJ7)
1Q, p, 7rQ amorphous silicon N (p
layer) 11 and a transparent electrode layer 12 on the light incident side are laminated. In figure b, the incident direction of light is reversed, and the transparent electrode 12, the p-type amorphous silicon Jm (pFJ)' 11, the amorphous silicon Ea (ill) 1o, nW' rear amorphous silicon is formed on the transparent glass substrate 13. A silicon layer (n layer) 9 and a sampling electrode or region 8 are stacked, and a and b are examples in which the manufacturing order is different.

Now, in general, sensor membranes apply a 1-ref 1-electric field from the outside to effectively pull out optical signal carriers (electrons and 1F holes) generated inside the sensor by light to the external circuit, and this point is different from solar cells. is different.

In addition, the n-layer 9 and the 9-layer 11 in Fig. 2 are prosokink layers 111, which prevent the injection of holes from the positive electrode and electrons from the negative electrode when an external voltage is applied. One layer 10 serves as a sensitive layer that suppresses the increase in dark current due to applied voltage and improves the S/N ratio of the optical signal, and generates the main optical signal. Therefore, the n-layer 9. The pJ layer 11 may be an insulating film (such as S102°Si3N4) or a layer of antimony trisulfide. By using such a prosokink layer, the structure may be such that injection of electrons or blocking holes is prevented due to the difference in work function between the sensitive layer and the conductive electrodes on both sides.

Next, FIGS. 3a and 3b show the operating state of the sensor using FIG. 2a as an example. As mentioned above, in order to use it as a sensor, a negative voltage is applied to the transparent electrode 12 and a positive voltage is applied to the sampling electrode or region 8 to form a drift electric field E (positive direction with respect to electrons) inside the sensor. Third
Figure a shows the optical signal charge 14 (
This is a simulated representation of the movement of electrons), where the optical signal charge 1
4 moves in the direction of the sampling voltage ('MA) due to the 1.lift electric field Σ in the sensor, while the sampling voltage (
Due to the diffusion phenomenon and the electric field E, some optical signal charge 14 also moves toward the input B. This situation is expressed using a band model in Figure 3, where the light incident on the sample link electrode A moves to the sample link electrode B, where it is accumulated and the lateral resolution is increased. deteriorate.

For this reason, research has been conducted to increase the resistance by adding the impurity Ganu (N2, B2H6, etc.) to the sensitive layer, but increasing the resistance also makes it more expensive to extract the optical signal to the outside. Since a drift electric field is required, low-voltage driving is difficult, and there is a problem in satisfying the three conditions of low-voltage driving and one high-resolution device.

OBJECTS OF THE INVENTION In view of the above-mentioned problems, the present invention provides a sensor having a structure that enables the use of a j-sensitivity layer having a low specific resistance and significantly improves the transverse direction.

SUMMARY OF THE INVENTION The present invention provides a photovoltaic device having a plurality of signal sampling link electrodes or regions and a selective impurity barrier region coupled thereto.
This is a photoelectric conversion device including a conversion layer, which suppresses lateral diffusion of optical signals by selective impurity barrier regions and improves lateral resolution.

DESCRIPTION OF EMBODIMENT 7 FIG. 4 shows a sensor structure according to an embodiment of the present invention in which the deep implantation region 15 shown in FIG. 4a is selectively formed for the purpose of improving lateral resolution, and FIG. Please use the same number for the same part. The manufacturing method shown in Fig. 4 is for a substrate 7 such as a semiconductor.
A signal sampling electrode or region 8 is selectively placed on top of the silanganu (5
iH4) etc. and an n-type layer made of amorphous silicon by adding gas 9.1) Threat 10. A p-type layer 11 is deposited, and then a p-type impurity such as boron B is selectively implanted to form an implanted region 15.

Next, a transparent electrode 12 such as ITO is laminated. If ion implantation alone is insufficient to form the deep implanted region 15, heat treatment in hydrogen plasma or a hydrogen furnace at a low temperature (approximately 300° C.), selective heat treatment using a laser, etc. may also be considered.

The injection material may also be a high resistance material such as oxygen, perforation, or carbon. Generally, in single crystal silicon, 30
Diffusion of impurities at low temperatures of around 0°C is extremely slow, 1-2μ
Forming a deep diffusion layer of m depth requires heat treatment for several tens of days or more, but in amorphous silicon it is possible by low temperature aging 121H in several hours or less, which is about 10 orders of magnitude faster than in the case of single crystal.

Of course, the injection region 15 can also be formed by thermal diffusion using a film source containing impurities.

Figure 4 is an energy band diagram of the operating state of the sensor with one seedling shown in figure a, with a negative voltage applied to the transparent electrode 12,
A stop voltage is applied to the sampling electrode or region 8, and the electric field E is drawn in the positive direction with respect to the electrons. The potential-like hill part 16 in Figure 4 is a deep injection region, and the optical signal charge 14 generated by the light on the - surface of the sample link electrode 5 is transferred to the 1-' rift 1- in the sensor.
The electric field E causes the sample link electric current to flow to +iA. At this time, due to the expansion 11·k phenomenon, it tends to bleed in the 1-yellow direction, but a potential barrier is formed in the lateral direction by the deep injection region 16, which prevents the diffusion phenomenon, and as a result, the adjacent sampling electrode B The amount of signal charge that moves and accumulates is small, and deterioration in lateral resolution is improved.

7.7 Similarly, FIGS. 5a and 5b show the structure and band (1?1) structure of the element when light is incident from the substrate side. On the substrate 13 such as glass, there is a transparent electrode layer 12 and a p-type layer. 11゜1 layer 10.n
A mold layer 9 and a signal sampling electrode or region 8 are formed, and a deep implant region 15 is formed. This formation may be done by using the sample link electrode 8 as a mask, or by using the layer 9 on the n-bar.
After that, patterning may be performed, and the sampling electrode 8 may be formed by implantation or diffusion. In this case as well, the deep injection region is injected deep into the layer 1o, that is, into the sensitive layer, and the optical signal charge 14 generated by the incidence of light moves toward the sample link electrode due to the drift electric field E, but at this time, the deep injection region The potential barrier of 16 makes it possible to prevent lateral diffusion even when using a sensitive layer with, for example, a low resistivity (approximately 10 Ω, Crn).

Furthermore, Figures 6a and b show that instead of injection or diffusion from the top surface of the photoelectric conversion sensor A, a diffusion source is fabricated on the substrate side between the sampling electrodes before forming the photoelectric conversion layer, as described above. This is an element in which a barrier region is provided by applying a heat treatment.

In a, 7 is a substrate such as a semiconductor, 8 is a signal sampling electrode or region, 9 is an amorphous silicon n-type layer, 10 is an i-layer, 11 is a p-type layer, 12 is a transparent electrode, 15
is an impurity barrier region, and 16 is a diffusion source for forming the barrier region 16. In this example as well, the signal charges 14 generated by light are prevented from diffusing in the lateral direction by the impurity barrier region, so that resolution is not degraded.

The figure also shows another example of forming an impurity barrier region using a diffusion source from the substrate, and the same parts as in the previous figure are given the same numbers.

In the example of FIG. 6, the barrier region 15 is present near the substrate 7° 13, and the barrier region 16 is absent on one side of the photoelectric conversion layer 10, so the photoelectric conversion efficiency is further improved. .

So far, we have mainly treated electrons as optical signal carriers, but holes can also be used, in which case a bias voltage can be applied in the opposite direction. Although we have taken amorphous silicon as an example of the embodiment, other amorphous materials such as germanium may be used, and even a photoelectric conversion layer made of recrystallized silicon produced by laser annealing of polycrystalline silicon, which has recently been applied, may also be used. Of course, medium-crystalline silicon, germanium, compound semiconductors, and compound amorphous materials are not necessarily suitable. However, in that case, a technique such as selective laser annealing is required to form a barrier in the deep implanted region. In addition, an n-type layer,
As described above, the p-type layer may be a prosogging layer or a short-Gy barrier layer that utilizes the difference in work function from the semiconducting electrode.

Effects of the Invention As described above, the present invention provides a WS with relatively low resistivity.
Improving the lateral resolution of amorphous silicon sensors with SMCim) can be achieved by applying techniques such as ion implantation, traditionally used in single-crystal silicon technology, compared to conventional Group I-■ compound sensors and others. This makes it possible to create a sensor that can be easily introduced into a silicon process without worrying about contamination compared to sensors based on amorphous compounds.

The sensor with this low resistivity sensitive layer has a large optical signal charge transfer stage regardless of the IJk material, such as amorphous, single crystal, or compound. This makes it possible to create a low-voltage drive sensor that can be driven at a lower power consumption compared to the conventional sensor, and is compatible with the recent reduction in power consumption.

[Brief explanation of drawings]

Figure 1 (a,), (b) Cross-sectional structure diagram of a conventional solar cell, its band model diagram, Figure 2 (a),
(b) is a conventional sensor 1+ with a structure similar to that of a solar cell.
7. Cross-sectional view of the II-built sensor structure, Figure 3 (a-),
, (b) are a conceptual diagram and a band model diagram of the operating state of the sensor, respectively, and FIGS. 4(a) and (b) are respectively the operation of a sensor with a structure having selectively deep injection regions according to an embodiment of the present invention. Conceptual cross-sectional diagram of the state, hand model diagram,
FIGS. 6(a) and 6(b) are conceptual cross-sectional views of the driving state of the sensor (?/I-structured element) of another embodiment of the present invention, and a Bund' model diagram; FIG. 6(a).(b) is the substrate side 1 for forming a deep impurity barrier region.
3. FIG. 3 is a structural diagram of an embodiment having a diffusion source in FIG. 7... Substrate such as semiconductor, 8... Signal sampling electrode or region, 9... N-type amorphous silicon layer (nJEl), 10...
Intrinsic amorphous silicon Ii@(i7t
d), 11... p-type amorphous silicon layer (
p layer), 12...transparent electrode layer, 13...
・Galanu substrate, 14... Optical signal charge (electron),
16... Deep implantation region, 16... Impurity diffusion source. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4 @ Figure 5

Claims (2)

[Claims] (1) a plurality of signal sampling electrodes or regions;
A photoelectric conversion layer coupled to the sampling electrode or region, and an impurity barrier region selectively formed in the photoelectric conversion layer for lateral separation of optical signals collected in the plurality of sampling electrodes or regions. Features of photoelectric conversion device. (2) The photoelectric conversion device according to claim 1, wherein the impurity barrier region extends from the surface layer or prosokink layer of the photoelectric conversion layer to the sensitive layer.