Amorphous semiconductor photocoupler

• US 6,403,984 B1
• Filed: 04/13/1995
• Issued: 06/11/2002
• Est. Priority Date: 04/15/1994
• Status: Expired due to Fees

• Current Assignee: Chulalongkorn University (Kingdom of Thailand)
• Original Assignee: Chulalongkorn University (Kingdom of Thailand)
• Inventors: Kruangam, Dusit
• Primary Examiner(s): Meier, Stephen D.
• Application Number:
  US08/421,089
• Time in Patent Office: 2,616 Days
• Field of Search: 257/80, 257/458
• US Class Current: 257/80
• CPC Class Codes: H01L 25/167 comprising optoelectronic devices, e.g. LED, photodiodes
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/346 containing porous silicon

Abstract

A photocoupler comprising a light emitting device and a light detecting device both of which are made of amorphous semiconductors. The light emitting device is an amorphous semiconductor thin film light emitting diode which emits light when stimulated by an electric stimuli. The light detecting device is either an amorphous semiconductor thin film solar cell which produces an electric signal when exposed to light or a photoconductive type amorphous semiconductor thin film whose electrical conductivity varies when exposed to light. Both of these light detecting devices thus give an indication of detected light. These types of photocouplers have low production costs, can be manufactured in different sizes are relatively easy to mass produce and are compact as well as light weight.

Claims

1. A photocoupler including:

an amorphous semiconductor thin film light emitting diode capable of emitting light in response to an electric stimuli;

an amorphous semiconductor photovoltaic light detecting means adapted to detect the emitted light of the thin film light emitting diode;

said light emitting diode comprising of a first thin film electrode, a plurality of amorphous semiconductor thin films, an optically transparent second thin film electrode, and an optically transparent substrate, arranged in a sandwich type manner, such an arrangement allowing emission of light through the optically transparent substrate when the light emitting diode is electrically stimulated; and

said photovoltaic light detecting means comprising of a first thin film electrode, a plurality of amorphous semiconductor thin films, an optically transparent second thin film electrode, and an optically transparent substrate, arranged in a sandwich type manner, the optically transparent substrates of both the light emitting diode and the light detecting means adapted to face each other with a spatial predetermined separation.

2. A photocoupler as in claim 1 wherein the light emitting diode and the photovoltaic light detecting means share a common optically transparent substrate so that the optically transparent thin film of the light emitting diode is positioned on one side of the optically transparent substrate and the optically transparent thin film of the photovoltaic light detecting means is positioned on the opposite side of the optically transparent substrate resulting in there being no spatial separation between the light emitting diode and the photovoltaic light detecting means.

3. The photocoupler of claim 1 wherein the spectrum of the light emitting diode lies from the infrared to the UV regions.

4. The photocoupler of claim 1 wherein the thin film electrode is selected from the group including aluminium and silver.

5. The photocoupler of claim 1 wherein the amorphous semiconductor thin films have p-i-n or n-i-p junctions arid are made of materials selected from the group including amorphous silicon (a-Si) amorphous silicon carbide (a-SiC) amorphous silicon nitride (a-SiN) amorphous silicon oxide (a-SiO) or the combination of these materials.

6. The photocoupler of claim 1 wherein the optically transparent thin film electrode is selected from the group including tin oxide, indium tin oxide, zinc oxide, or a combination of these.

7. The photocoupler of claim 1 wherein the optically transparent substrate is a glass sheet.

8. The photocoupler of claim 1 wherein the photocoupler includes an insulating material adapted to shield the photocoupler from any external light.

9. The photocoupler of claim 8 wherein there are electrical terminals extending through the insulating material so as to allow electrical signals to pass from and/or to the photocoupler.

10. The photocoupler of claim 1 wherein the thicknesses of the optically transparent substrate, transparent electrode, p-i-n layers and first electrode are preferably 0.5-1 mm, 200 angstroms, 150 angstroms, 500 angstroms, 500 angstroms and 2000 angstroms, respectively.

11. The photocoupler of claim 1 wherein the typical spatial separation between the light emitting diode and the photovoltaic light detecting means is between 1 to 10 mm.

12. The photocoupler of claim 1 wherein the photovoltaic light detecting means is sensitive to light ranging from the infrared to the ultraviolet regions.

13. The photocoupler of claim 1 wherein the optically transparent substrate for the said light emitting diode and photovoltaic light detecting device can be any material provide it is optically transparent to the wavelength emitted by the light emitting diode.

24. The photocoupler of claim 1 further adapted to allow for the detection of an object when placed in between the light emitting diode and the photovoltaic light detecting device so as to prevent at least some of the emitted light reaching the light detecting device.

14. A photocoupler including:

an amorphous semiconductor thin film light emitting diode capable of emitting light in response to an electric stimuli;

an amorphous semiconductor photoconductive light detecting means adapted to detect the light emitted by the thin film light emitting diode;

said light emitting diode comprising of a first thin film electrode, a plurality of amorphous semiconductor thin films, an optically transparent second thin film electrode arid an optically transparent substrate, arranged in a sandwich type manner such an arrangement allowing emission of light through the optically transparent substrate when the light emitting diode is electrically stimulated, and

said photoconductive light detecting means comprising of an optically transparent substrate, an amorphous silicon thin film and an ohmic thin film electrode, in a sandwich type arrangement the said photoconductive light detecting means positioned so that its optically transparent substrate faces the optically transparent substrate of the light emitting diode with a spatial predetermined separation.

15. A photocoupler as in claim 14 but wherein the light emitting diode and the photoconductive light detecting means share a common optically transparent substrate so that the optically transparent thin film of the light emitting diode is positioned on one side of the optically transparent substrate and the optically transparent thin film of the photoconductive light detecting means is positioned on the opposite side of the optically transparent substrate resulting in there being no spatial separation between the light emitting diode and the photoconductive light detecting means.

16. The photocoupler of claim 14 wherein the spectrum of the light emitting diode can be from the infrared to the UV regions.

17. The photocoupler of claim 14 wherein the thin film electrode is selected from the group including aluminium and silver.

18. The photocoupler of claim 14 wherein the amorphous semiconductor thin films have p-i-n or n-i-p junctions and are made of materials selected from the group including amorphous silicon (a-Si) amorphous silicon carbide (a-SiC) amorphous silicon nitride (a-SiN) amorphous silicon oxide (a-SiO) or the combination of these materials.

19. The photocoupler of claim 14 wherein the ohmic thin film electrode of the photoconductive light detecting means is selected from the group including aluminium and silver.

20. The photocoupler of claim 14 wherein the optically transparent substrate is a glass sheet.

21. The photocoupler of claim 14 wherein the amorphous silicon thin film of the photoconductor is intrinsically or lightly doped.

22. The photocoupler of claim 14 wherein the photocoupler is insulated from external light by insulating material.

23. The photocoupler of claim 14 wherein the thicknesses of the optically transparent substrate, transparent electrode, p-i-n layers and first electrode are preferably 0.5-1 mm, 200 angstroms, 150 angstroms, 500 angstroms, 500 angstroms and 2000 angstroms, respectively.

25. The photocoupler of claim 14 further adapted to allow for the detection of an object when placed in between the light emitting diode and the photovoltaic light detecting device so as to prevent at least some of the emitted light reaching the light detecting device.