JPS60234366A - light driven thyristor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a thyristor that can be gate-controlled by an optical signal, and in particular has a high ignition sensitivity by the optical signal and a sufficient rate of increase in critical off-torque pressure. This invention relates to an original AD type thyristor that can provide a large amount of power.

[Back mold of invention]

Thyristors, which are switching elements with a 4ttti structure, are widely used for low-power but high-power switching. In addition, light-activated thyristors, which can be triggered directly by light energy, have appeared, and their applications are expected to continue to expand.

This light-driven thyristor, like the drowsiness signal-triggered thyristor, is basically composed of at least a four-layer pnpn semicircular body and a pair of main electrodes in ohmic contact with the inner and outer layers. However, it does not have a trigger terminal, and can be turned on by irradiating a predetermined part of the semi-coated layer with light.
For this reason, (1) electrical isolation between the main circuit and the control circuit that still has voltage resistance is required, or the control circuit becomes complicated even if the main circuit's voltage is high. There is no such thing.

(2) It is resistant to noise caused by magnetic induction and has little risk of malfunction.

In recent years, there have been many expectations for its application to thyristor conversion devices for high-pressure direct current inflows.

By the way, one of the problems faced by thyristor elements in such applications is how to improve the light ignition sensitivity without impairing the critical off-torque pressure rise rate (abbreviated as dv/dt tolerance). There is something to raise.

FIG. 1 shows an example of a light-dynamic thyristor.

In FIG. 1, an optical thyristor (light-driven thyristor) 100 is an n-pace J*1. p base layer 2.
p emitter layer 3. n emitter layer 4. The above n-emitter layer 3
anode electrode in ohmic contact with5. A cathode electrode 6 in ohmic contact with the n-emitter layer 4. n emitter lfi 4LI provided separately from n emitter layer 4
and 400 and the n-base layer 2, electrode marks 600. and 600. It also includes a light guide 7 that irradiates a predetermined surface area of the p-base node 2 with an optical signal.

When a forward voltage is applied between the electrodes 5 and 6 and an optical signal is sent by the light kite 7 to the original thyristor 100 which is in the off state, the p base layer 2, the n base layer 1,
In addition, Ib is generated in the light at 'fH of the p emitter layer 3, and this flows into the cathode electrode 6 as shown by the arrow.

As a result, a potential gradient is generated in the p base layer 2 in the lateral direction, and a positive potential vo is generated in the n base layer 2 immediately below the inner periphery of the n emitter layer 400.

The magnitude of this potential vo is given by the product of the lateral resistance pB of the n-base layer 2 and the generated photocurrent Ib.
. When approaches the built-in% pressure of the junction between the n-emitter layer 400 and the n-base layer 2, the n-emitter layer 40
Ignition starts from the inner circumferential portion of 0, and the optical thyristor 100 is activated.

The above is the firing operation of the optical thyristor. On the other hand, when the optical thyristor 100 is in the off state, the n-base layer 2
A forward pressure V is applied to the pn junction between the n emitter layer 1 and the n emitter layer 1, and this pn junction is in a reverse bias state. In this state, when a change dv/dt occurs in the forward voltage V due to noise etc., a displacement (current flowing through the capacitor) Ia appears in this p-n junction, but this displacement current Id has the polarity of the photocurrent 1b and therefore this displacement t
When N and Id become large, the photocircuit 100 will be fired even by this tKId, resulting in false firing.

Therefore, the difficulty in causing ignition due to the change in forward voltage V dv/dt is called dv/dt tolerance, and if this is small, erroneous ignition is likely to occur due to noise etc.
It is desirable that this dv/dt tolerance is large.

However, as is clear from the above, this dv/dt tolerance is the same as the light ignition sensitivity, and the p base Wl
The lateral resistance of 2 is determined by pB, therefore, this first
In the optical thyristor 100 shown in the figure, when trying to increase the light ignition sensitivity, erroneous ignition is likely to occur due to the change in dv/dt, so it is necessary to improve both the light ignition sensitivity and the dv/dt tolerance. The disadvantage is that it is difficult to

FIG. 2 shows an example of an optical thyristor 110 in which the light ignition sensitivity can be changed independently of the dv/dtiiit amount.

This optical thyristor 110 is the optical thyristor 100 in FIG.
The difference is that the electrodes 600 for the n emitter layer 400 and the p base layer 2 are divided, and each electrode 601. 602, these 9 are connected by a resistor 8, and the irradiation position of the optical signal applied by the light guide 7 is the surface area of the n emitter layer 4000.

When a tortoise pressure is applied to the optical thyristor 110 in the internal direction and an optical signal is irradiated from the light guide 7, a photocurrent Ib is generated inside the optical thyristor 100 in FIG.
However, in this optical thyristor 110, light passes through the n-emitter layer 400 and enters the n-emitter layer 400, ! = 1) A photovoltaic effect works at the junction of the base layer 2 (J3 junction), and a voltage is generated at this junction J3. On the other hand, correspondingly, the electrode 600 has two '#L&
Since these are divided into 601 and 602 and connected by a resistor 8, the voltage generated at the J3 junction described above causes the n emitter layer 400 → J3 junction → p base layer 2 → electrode 602 → resistor 8 → electrode 601→n emitter layer 400
The photovoltaic current ip circulates in the direction .

Since this photovoltaic current Ip flows in the same direction as the above-mentioned photovoltaic current 1b in the n-base layer 2, it acts to further increase the above-mentioned voltage v0 and increases the ignition sensitivity. .

Furthermore, since the resistor 8 is inserted, the photovoltaic current Ip
A voltage drop occurs across this resistor 8, but since this voltage drop serves to forward bias the J3 junction, this also improves the ignition sensitivity.

On the other hand, the current Ip flowing through the photocell only appears when an optical signal is irradiated, and does not occur at all depending on the amount of change dv/dt.

Therefore, the effect of improving the ignition sensitivity due to the photocell current Ip appears only when a regular optical signal is incident, and there is no effect that either sufficiently improves the ignition sensitivity or reduces the dv/di resistance. Therefore, according to this optical thyristor 110, the ignition sensitivity can be improved by a light amount without reducing the dv/dt tolerance.

Apart from this, d without affecting the ignition sensitivity can also be used.
Photosilisk with improved v/d tolerance is disclosed in, for example, US Pat. No. 4,122,480 Mei III-11I.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and its object is to provide a photothyristor that can further improve the dv/dt tolerance while increasing the ignition sensitivity through photovoltaic action. is to provide.

[Summary of the invention]

To achieve this objective, the present invention proposes to increase the resistance of the external conductive path used to improve the ignition sensitivity by photovoltaic action.
The present invention is characterized in that a part of the displacement '1' generated by the change in earth pressure in the +V direction is channeled, so that when displacement distribution occurs, the ignition sensitivity is suppressed.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The optical thyristor according to the present invention will be explained in detail below with reference to one embodiment shown in the drawings.

3 and 4 show one embodiment of the present invention, FIG. 3 is a plan view, and FIG. 4 is a sectional view taken along line A-A' in FIG.
In these figures, addition is the p base layer.

Reference numeral 61 denotes an electrode in ohmic contact with this p-base layer, and the rest is the same as the optical thyristor 110 shown in FIG. Incidentally, the entire original thyristor of the present invention according to FIGS. 3 and 4 is represented by 120.

The p-base Wi 20 is formed in 1 ml of n-base completely independently of the original n-base layer 2,
At this time, isolation between the p-base layer 1 and the p-base layer 2 is provided by the pn junction between the p-base layer 1 and the n-base layer 1.

The electrode 61 is connected to the electrode 601 by a low-resistance external conductive path C, which serves to connect the P layer 1 and the portion of the N base layer 2 below the electrode 602 via the resistor 8. do.

Next, the operation of this embodiment will be explained.

First, the operation at the time of ignition based on the original signal will be explained.

As shown in FIG. 4, from the light guide 7 to the n emitter j
When an optical signal is irradiated to #400, a photocurrent ib is generated in the n-base layer 2, n-base/ml, and p-emitter layer 3 regions of the original thyristor 110 and 1st layer explained in FIG. This passes laterally through the n-base layer 2 and forms the cathode 6.
The light flows into the light, forward biasing the emitter junction between the n-emitter layer 400 and the n-base layer 2, which serves as a light receiving section for optical signals, and activating the ignition effect.

On the other hand, in parallel with this, this is also the optical thyristor 1 in Fig. 2.
Similarly to 10, a photovoltaic current Ip is generated due to the photovoltaic effect at the pn junction consisting of the n emitter layer 400 and the n base layer 2, and this current Ip flows from the p base layer 2 to the electrode 602.
→ Resistor 8 → Electrode 601 → N emitter layer 400 → P base layer 2. The pn junction is circulated through this path, and this pn junction is J-biased to further facilitate ignition.

Therefore, the original thyristor 120 according to this embodiment can provide high ignition sensitivity and always ensure ignition by optical signals.

Note that the optical zyristor 120 according to this embodiment is provided with a conductive path C), which allows the 'electrodes 601 and 602 to
is electrically coupled from the 'electrode 61 to the p-base layer, but the photovoltaic current Ip generated during the ignition operation by the above-mentioned optical signal does not flow from the 'electrode 61 to the p-base layer. The reason for this is the following 9. That is, in a state in which ignition is about to occur, that is, in a forward blocking state, a voltage is applied that is negative to the cathode terminal K and positive to the anode terminal A, and therefore,
This is because the junction between the pE layer 1 and the n base layer 1 is in a reverse bias state. As a result, depending on the presence of the conductive path C, the above-mentioned improvement in ignition sensitivity can be obtained even though the ignition operation by the optical signal has no effect at all.

Next, the change in forward voltage V due to noise etc. dv/d
t or F:l] is added.
This will be explained using figures.

When the IIM direction 0 change dv/di is carried between the anode terminal A and the cathode terminal 1 (n base layer 2 and n
A displacement current IdO is generated almost uniformly in the vicinity of the junction with the base layer 1, which flows laterally through the n-base layer 2 and into the cathode electrode 6. And this return position is DicI
The value of do becomes greater than or equal to the value of n emitter Jfi40
The magnitude of the voltage drop due to the lateral resistance of the n-base layer 2 immediately below the n-emitter I layer 4oo and the n-base layer 2
As the potential at the junction between the two approaches the diffusion potential, the photothyristor 120 begins to fire, resulting in false firing.

Therefore, in the optical thyristor 120 according to this embodiment,
In contrast to the original n-base layer 2, there is a p-base J that is isolated and exists independently by the n-base layer 1.
WI20 fJ' knee is provided, and when the above-mentioned displacement current IdolJ''-appears, this p
A displacement current Id1 appears in the same manner near the junction between the E1 layer and the n-base I@1, and this current Id1 pushes the conductive path C1 from the electrode 61 through the resistor 8 to the electrode 602.
and enters the p-<-s layer 2 from this electrode 602,
It joins with the displacement current Ido and flows into the cathode electrode 6. It is unnecessary to explain that the displacement peaks KIao and Idx at this time are generated at approximately the same current density.

In this way the displacement from n pace 1 addition it 171j
When Idx flows through the resistor 8, a Narita with the polarity shown is generated in the resistor 8, and this voltage is applied between the 'electrodes 601 and 602, thereby n emp layer 400 Torbase Jfl 2 This acts to reverse bias the emitter-base junction between the two and lower the firing sensitivity.

Therefore, according to the optical thyristor 120 according to this embodiment, when a change in forward voltage dv/dt is applied, the ignition sensitivity is kept low only at that time, and a large dv/dt withstand capacity is achieved. After all, high ignition sensitivity to optical signals? big dv while keeping
/dt welfare can be given.

When compared by the experiment flJ consisting of The dramatic amount of dt is the optical radiation risk 11 in Figure 2.
This was an improvement of about 1.7 times compared to 0.

FIG. 6 shows an optical switch 1 lister 1 according to another embodiment of the present invention.
This original thyristor 130 is different from the original thyristor 120 in the embodiment of FIG.
The only difference is that the seventh groove M is used as a means for providing the E1 layer independently from the original N base layer 2, and the other structure and overall functions are the same as that of the embodiment shown in FIG. is the same as

〔Effect of the invention〕

As explained above, according to the present invention, the d v /d t 1liIi of the optical thyristor which aims to improve the ignition sensitivity by the photovoltaic action with respect to the ignition operation by the optical signal,
Since the ignition sensitivity can be increased independently of the improvement, the drawbacks of the prior art can be eliminated, and the optical thyristor has the high optical ignition sensitivity and sufficient dv/dt resistance required for the optical thyristor. A total of Km can be easily provided.

[Brief explanation of drawings]

Figure 1 is Koukou! A sectional view showing a conventional example of a 4tI type thyristor, Fig. 2 a sectional view showing an example of a pioneer #A type thyristor with improved light ignition sensitivity, and Fig. 3 an example of an optically driven thyristor according to the present invention. 4 is a sectional view taken along the line A-A' in FIG. 3, FIG. 5 is an explanatory diagram showing the operation of the light-driven thyristor shown in FIGS. 3 and 4, and FIG.
The figure is a sectional view showing another embodiment of the present invention. 1...n base layer, 2. Add...p base layer, 3...p emitter layer, 4.40. 40
0... curve n emitter layer, 5. 6.60.61. 60
1. 602・−・−・、! I--mic electrode, 7...
...Light guide, 8...Resistance. Figure 1 Figure 2 Figure 3 Figure 4 Continued from page 1 [Phase] Inventor Tsutomu Yao Saiwai-cho, Hitachi City: On-site

Claims (1)

[Claims] 1. A first emitter layer of a first diagonal type and a first emitter layer of a second conductivity type.
The semiconductor substrate includes a base layer, a second base layer of a first conductivity type, and a semiconductor substrate having a 41-layer structure extending from the emitter layer of a 24th conductivity type formed on a selected portion of the surface of the second base layer. , an independent part of the surface of the second emitter skin is used as a light-receiving surface for the gating optical signal, and the second emitter layer serving as the light-receiving surface and the second base layer are selected. In a light-driven thyristor in which an external conductive path with a sufficient resistance value is formed between a part of the surface area, the first conductive type thyristor is independent of the second base j- of the first conductive turtle type. A light-driven thyristor characterized in that a second base layer is provided, and an external conductive path is formed between the independent second base layer and the second emitter layer of the second conductivity type, which serves as the light-receiving surface. . 2. In the first claim, the independent first claim
A light-driven thyristor characterized in that it is formed by isolation by a pn junction between the guiding turtle type second base layer or the second guiding type first base layer. 3. In claim 1, the independent @4
1. A thyristor of the 1-type thyristor, characterized in that the 2-base increase per year is formed by isolation by a moat groove provided on the surface of the second base layer of the first conductivity type.