JP2716068B2 - Semiconductor device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device including a semiconductor light emitting element and a semiconductor light receiving element that receives light from the light emitting element.

[Conventional technology]

Conventionally, a semiconductor light-emitting element, and a semiconductor light-receiving element that receives the light of this light-emitting element and outputs a current,
There is a semiconductor device further provided with a semiconductor element driven by the output of the light receiving element. In this type of device, the semiconductor light emitting element and the semiconductor light receiving element transmit and receive light via a transparent (light transmitting) insulating layer. Therefore, the semiconductor light emitting element and the semiconductor light receiving element are completely electrically connected. It has the characteristic that it can be separated.

Examples of the semiconductor device as described above include an infrared LED (light emitting element), a single crystal silicon solar cell (light receiving element), and an FET.
(Semiconductor elements).

In this semiconductor device, the FET performs a switching operation in response to an input signal. That is, when an input signal is applied to the infrared LED, the infrared LED emits light, which enters the solar cell. A photovoltaic power is generated in a solar cell that receives light. The solar cell is connected between the gate and the source of the FET, and an electromotive force is applied between the gate and the source, thereby conducting between the source and the drain of the FET to be turned on.

[Problems to be solved by the invention]

Conventional semiconductor devices turn on after receiving an input signal.
The time (response speed) until the device is turned off fluctuates with a change in temperature and is not stable.

The instability of the response speed is due to the fact that the output current of the solar cell fluctuates greatly with a change in temperature. That is, in the combination of an infrared LED and a single-crystal silicon solar cell in a conventional semiconductor device, the output current of the solar cell fluctuates greatly with a change in temperature. The wavelength of the infrared LED is tuned to the wavelength at which the sensitivity of the single crystal silicon solar cell peaks, but in this case, the fluctuation of the light output of the infrared LED directly appears as the fluctuation of the output current of the solar cell . The variation of the light output of the infrared LED decreases by 40% when the temperature rises from room temperature (25 ° C.) to 80 ° C. In response, the output current of the single crystal silicon solar cell also drops by about 40%.

On the other hand, when an electromotive force is generated in response to an input signal,
A large voltage is not immediately applied between the gate and the source of the solar cell, but the output current from the solar cell gradually approaches the voltage of the electromotive force of the solar cell as the capacity (capacitance) between the gate and the source is charged. go. Of course, the higher the output current of the solar cell, the sooner it will reach the voltage at which the FET can be turned on. Therefore, when the output current of the solar cell decreases as described above, it takes time to charge the gate-source capacitance, and the turn-on state is delayed accordingly.

As described above, in the conventional semiconductor device, the response speed decreases as the temperature increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor device having a characteristic in which output fluctuation due to a temperature change is small.

[Means for solving the problem]

A semiconductor device according to the present invention has a semiconductor light receiving element and a semiconductor light emitting element. A semiconductor light receiving element is an element having a configuration in which, in a predetermined wavelength region, the light receiving sensitivity decreases as the wavelength of the received light increases, and the light receiving sensitivity characteristic shifts to a longer wavelength side with an increase in temperature. is there. The semiconductor light emitting element has a light emission peak in a predetermined wavelength region, and the light output amount decreases with an increase in temperature, and outputs light to the light receiving element.

The light-emitting element is one of a group consisting of an LED, a semiconductor laser, and an electroluminescence element, has a light emission peak in a wavelength range of about 550 nm to 800 nm, and the light-receiving element is a solar cell made of amorphous silicon. Preferably, it is a battery.

Further, the light emitting element is a red LED having a light emission peak near 600 nm, and the light receiving element is about 600 nm to about 70 nm.
It is preferable that the solar cell is made of amorphous silicon and has a sensitivity characteristic in which the light receiving sensitivity decreases as the wavelength increases in the wavelength range of 0 nm.

Further, the semiconductor device may further include a semiconductor element driven by an output of the light receiving element.

[Action]

In the semiconductor device according to the present invention, the light output fluctuation due to the temperature change of the semiconductor light emitting element (hereinafter simply referred to as light emitting element) and the light receiving sensitivity fluctuation due to the temperature change of the semiconductor light receiving element (hereinafter simply referred to as light receiving element). However, by using an element that is the opposite, as a result, the output of the light receiving element does not fluctuate much with a change in temperature. Therefore, the temperature characteristics of the output of the semiconductor device are improved.

The light receiving element has a sensitivity characteristic in which the light receiving sensitivity decreases with an increase in the wavelength in a region including the wavelength of the light of the light emitting element, and the temperature characteristic shifts to a longer wavelength side with an increase in temperature (temperature change). The optical forbidden band Egopt changes), so that the light receiving sensitivity increases as the temperature rises. The increase in the light receiving sensitivity compensates for the decrease in the light output amount due to the temperature rise in the light emitting element, and suppresses the fluctuation as a whole.

As the light emitting element, an LED, a semiconductor laser, an electroluminescence element, or the like is used.As the light receiving element, a solar cell or the like is used.If the LED is a red LED and the solar cell is a solar electron made of amorphous silicon, The degree of improvement in temperature characteristics is large.

In particular, the light emitting element is one of a group consisting of an LED, a semiconductor laser, and an electroluminescent element, has a light emission peak in a wavelength range of about 550 nm to 800 nm, and the light receiving element is a solar cell made of amorphous silicon. If it is, the output fluctuation of the light receiving element can be further suppressed.

The light-emitting element is a red LED having an emission peak near 600 nm, and the light-receiving element is made of amorphous silicon exhibiting sensitivity characteristics in which the light-receiving sensitivity decreases with an increase in wavelength in a wavelength range of about 600 nm to about 700 nm. In the case of a solar cell, the output fluctuation of the light receiving element can be further suppressed as described above.

Furthermore, if a semiconductor element driven by the output of the light receiving element is further provided, there is no need to prepare or connect a semiconductor element again, and it is easy to use.

〔Example〕

Hereinafter, a semiconductor device of the present invention will be described in detail with reference to the drawings showing an example thereof.

FIG. 1A is a circuit diagram of a semiconductor device according to one embodiment of the present invention, and FIG. 1B is a schematic sectional view.

The semiconductor device 1 includes an LED (light emitting diode) L ₁ ,
Consisting field effect transistors connected TR ₁ as switched driven by the output of the solar cell DA ₁ and the solar cell DA ₁ receives light L _1.

The transistor TR ₁ is formed on the semiconductor substrate 2,
The solar cell DA ₁ (3) is formed on the substrate 2 with the insulating layer 5 interposed therebetween. The solar cell DA ₁ (3) and the LED L ₁ (4) face each other with the transparent insulating layer 6 interposed therebetween so that light of the LED L ₁ enters the solar cell DA ₁ . Solar DA ₁ has taken an array configuration in which a plurality are connected in series to increase output voltage.

The semiconductor device 1 is manufactured, for example, as follows.

A state in which a solar cell DA ₁ (3) is laminated and formed on a semiconductor substrate 2 on which a transistor TR ₁ is formed, and an LEDL ₁ (4) manufactured separately are spaced apart in a mold by a predetermined distance. And the gap is filled with a transparent insulating material such as a transparent resin to be integrated.

When an electric input signal is input to input terminals T ₁ and T ₂ , LEDL
₁ emits light, the light enters the solar cell DA _1. In the solar cell DA ₁ receives the light electromotive force is generated, the voltage between the gate and source of the transistor TR ₁ is applied, thereby the transistor TR ₁ is turned on state. Transistor TR ₁ is switched driven by the output of the solar cell DA _1.

In this semiconductor device, the output current fluctuation of the solar cell DA ₁ due to temperature changes, are significantly reduced compared with the conventional.

The straight line C in FIG. 3 is the solar cell DA ₁ of the semiconductor device of the embodiment.
Represents the relationship between the output current and the temperature, and the straight line D in the figure represents the relationship between the output current and the temperature of the solar cell of the conventional semiconductor device.

In the solar cell of the embodiment, the output current fluctuation is −0.44% / ° C.
The reduction rate at 80 ° C. is about 25% compared to that at room temperature. On the other hand, in the conventional solar cell, the output current fluctuation is −
0.8% / ° C., the rate of reduction at 80 ° C. exceeds about 40%. As described above, in the solar cell of the embodiment, the fluctuation is about half that of the conventional solar cell.

For that variation due to the temperature change of the output current of the solar cell DA ₁ in the embodiment is reduced will be described in more detail.

It said LEDL ₁ is a red LED with a sharp emission peak at a wavelength of approximately 660 nm. Looking at the relationship between the light emission amount and temperature of this LEDL ₁ ,
As shown by the straight line E in FIG.
Light intensity from 150% to 60% for temperature changes from -20 ° C to 80 ° C
It rapidly decreases to. That is, the light output of LEDL ₁ is (a negative change) that decreases rapidly with increasing temperature.

Meanwhile, solar cell DA ₁ is a solar cell made of amorphous silicon. As shown by curves A and B in FIG. 2, this solar cell DA ₁ has a light receiving sensitivity that increases sharply with an increase in wavelength at a wavelength of about 600 nm to about 700 nm, which is the light wavelength (660 nm) of LED L _1. To decrease. In FIG. 2, curve A represents temperature T _1.
The curve B in FIG. 2 shows the spectral sensitivity characteristic at the temperature T ₂
(T ₁ <T ₂ ). In the case of this solar cell DA ₁ , the optical bandgap Egopt increases as the temperature rises.
Is reduced so that the spectral sensitivity characteristic shifts to the longer wavelength side. Therefore, when viewed at a wavelength of light LEDL _1, whereas the sensitivity A ₁ in the temperature T _1, the temperature T ₂ sensitivity
Sensitivity is enhanced with the B ₁ and the temperature rise. Of course, as the temperature decreases, the spectral sensitivity characteristic shifts to the shorter wavelength side.

Here, previously kept constant the light quantity of the light source LEDL1, shows the change in the output current in the case of changing only the temperature of the solar cell DA ₁ to -40 ° C. to 80 ° C. in a straight line F of FIG. 5. This fifth
As is clear from the straight line F in the figure, the output current with respect to the temperature change is 60% to 150% based on 20 ° C (the standard is 20%).
° C) (with a positive change).

By combining this solar cell DA ₁ that makes a positive change and the LEDL ₁ that makes a negative change, the mutual fluctuation due to the temperature change is canceled out, and even if there is a temperature change, the output current of the solar cell DA ₁ Fluctuations are suppressed.

Thus, state of charge of the electromotive force generated initial gate-source capacitance (indicated by the capacitor C ₁ in FIG. 1 (a)) is less changed even if the temperature changes. Therefore, the time from when the input signal is received to when the turn-on state is attained becomes substantially constant, and the response speed becomes stable regardless of the temperature change.

[Other embodiments]

 The light emitting element and the light receiving element are not limited to those described above.

However, it is easy to use a light source having a strong monochromaticity with a sharp emission peak. For example, in the above embodiment, the LED is 660 nm
Although it had an emission peak in the vicinity, in the case of a solar cell made of amorphous silicon, if it has an emission peak in a wavelength range of about 550 nm to 800 nm, the exemplary red LE
The semiconductor device has characteristics close to D. Of course, the solar cell may be made of a material other than amorphous silicon.

Further, in the above embodiment, the light receiving element is laminated on the surface, and the semiconductor substrate on which the semiconductor element is formed, and the separately manufactured light emitting element are manufactured in such a manner that the light emitting element is bonded using a transparent resin in a mold. However, the present invention is not limited to this, and an insulating layer, a light receiving element, a transparent insulating layer, and a light emitting element may be sequentially laminated and formed on a semiconductor substrate on which a semiconductor element is formed.

Furthermore, even if the semiconductor device does not include a semiconductor element driven by the output of the light receiving element and is configured by a light emitting element and a light receiving element, the OEIC (Opt Electric Integrated
Circuit).

〔The invention's effect〕

As described above, in the semiconductor device according to the present invention, the change in the optical output due to the temperature change of the light emitting element and the change in the output due to the temperature change of the light receiving element cancel each other, so that the output temperature characteristics are excellent.

In addition, by using a light-emitting element or a light-receiving element having a specific structure and a specific sensitivity characteristic in a specific wavelength range, the temperature characteristics of the light-emitting element and the light-receiving element appropriately correspond, and the output fluctuation of the light-receiving element is Can be suppressed.

Further, when a semiconductor element driven by the output of the light receiving element is further provided, it is easy to use.

[Brief description of the drawings]

FIG. 1A is an electric circuit diagram of a semiconductor device according to an embodiment of the present invention, FIG. 1B is a schematic sectional view thereof, and FIG. 2 shows a spectral sensitivity characteristic of a solar cell of the semiconductor device. Figure,
FIG. 3 is a diagram showing the relationship between the output current and the temperature of each solar cell of the semiconductor device and the conventional semiconductor device. FIG. 4 is a diagram showing the relationship between the light output amount of the LED of the semiconductor device and the temperature. FIG. 5 shows the LE in the solar cell of the above embodiment.
FIG. 6 is a diagram illustrating a relationship between temperature and sensitivity at a wavelength of light emitted by D. 1 ...... semiconductor device, L ₁ ...... LED (light emitting element), DA ₁ ...... solar cell (light receiving element), TR ₁ ...... transistor (semiconductor device)

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-1006878 (JP, A) JP-A-58-225322 (JP, A) JP-A-54-114192 (JP, A) JP-A Sho 60- 250718 (JP, A) JP-A-58-100469 (JP, A) JP-A-58-101476 (JP, A)

Claims (4)

(57) [Claims] A semiconductor light-receiving element in which light-receiving sensitivity decreases as the wavelength of light to be received increases in a predetermined wavelength region, and whose light-receiving sensitivity characteristic shifts to a longer wavelength side with an increase in temperature; While having an emission peak in a predetermined wavelength region,
A semiconductor device comprising: a semiconductor light emitting element that outputs light to the light receiving element, the amount of light output decreasing with an increase in temperature. 2. The light-emitting device according to claim 1, wherein the light-emitting device is one of a group consisting of an LED, a semiconductor laser, and an electroluminescence device, and has a light emission peak in a wavelength range of about 550 nm to 800 nm. The semiconductor device according to claim 1, wherein the semiconductor device is a solar cell. 3. The light emitting device according to claim 1, wherein the light emitting device is a red LED having a light emission peak near 600 nm, and the light receiving device has a sensitivity characteristic in which the light receiving sensitivity decreases as the wavelength increases in a wavelength range of about 600 nm to about 700 nm. 2. A solar cell comprising the amorphous silicon shown in claim 1.
13. The semiconductor device according to claim 1. 4. The semiconductor device according to claim 1, further comprising a semiconductor element driven by an output of said light receiving element.