GB2034518A - Light-activated p-i-n switch - Google Patents
Light-activated p-i-n switch Download PDFInfo
- Publication number
- GB2034518A GB2034518A GB7935971A GB7935971A GB2034518A GB 2034518 A GB2034518 A GB 2034518A GB 7935971 A GB7935971 A GB 7935971A GB 7935971 A GB7935971 A GB 7935971A GB 2034518 A GB2034518 A GB 2034518A
- Authority
- GB
- United Kingdom
- Prior art keywords
- region
- light
- switch
- impurity
- regions
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000004065 semiconductor Substances 0.000 claims abstract description 21
- 239000012535 impurity Substances 0.000 claims description 20
- 230000005684 electric field Effects 0.000 description 17
- 230000007423 decrease Effects 0.000 description 7
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 230000008878 coupling Effects 0.000 description 5
- 238000010168 coupling process Methods 0.000 description 5
- 238000005859 coupling reaction Methods 0.000 description 5
- 238000010521 absorption reaction Methods 0.000 description 4
- 239000004020 conductor Substances 0.000 description 4
- 230000005670 electromagnetic radiation Effects 0.000 description 4
- 239000003574 free electron Substances 0.000 description 4
- 230000000903 blocking effect Effects 0.000 description 3
- 239000002019 doping agent Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052787 antimony Inorganic materials 0.000 description 1
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000002939 deleterious effect Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 229910052733 gallium Inorganic materials 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 229920002120 photoresistant polymer Polymers 0.000 description 1
- 230000006335 response to radiation Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10F30/00—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors
- H10F30/20—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors
- H10F30/21—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation
- H10F30/22—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation the devices having only one potential barrier, e.g. photodiodes
- H10F30/223—Individual radiation-sensitive semiconductor devices in which radiation controls the flow of current through the devices, e.g. photodetectors the devices having potential barriers, e.g. phototransistors the devices being sensitive to infrared, visible or ultraviolet radiation the devices having only one potential barrier, e.g. photodiodes the potential barrier being a PIN barrier
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
- H03K17/78—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used using opto-electronic devices, i.e. light-emitting and photoelectric devices electrically- or optically-coupled
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
- H10F77/00—Constructional details of devices covered by this subclass
- H10F77/20—Electrodes
- H10F77/206—Electrodes for devices having potential barriers
Landscapes
- Thyristors (AREA)
- Led Devices (AREA)
- Bipolar Transistors (AREA)
- Light Receiving Elements (AREA)
Abstract
A light-activated semiconductor switch includes a p-i-n rectifier. An emitter electrode 24 disposed on the surface of the p<+> region 14 includes openings therein or a grid structure for allowing light to impinge on the p<+> region. A collector electrode 22 is disposed on the surface of the n<+> region 16, which collector electrode may also include a grid structure for allowing light to impinge on the n<+> region. <IMAGE>
Description
SPECIFICATION
Light-activated p-i-n switch
This invention relates to the field of light-activated or light-sensitive semiconductor devices and more particularly to semiconductor switches gated by light ratiation.
Light-activated-silicon-switches (LASS) promise to be very useful in power electronic systems. The major accepted advantages of LASS are: electrical isolation of the control circuit from the power circuit; very fast turn-on; simultaneous turn-on of related units; reduction of cusioning components when units are series connected; and insensitivity to electrical noise. In addition, there are certain other advantages such as lower cabling weight for fiber optic cable as compared to copper cable.
Light-activated thyristors will be particularly useful in electronic power circuits. They can be turned on when optically excited by means of a laser or other light source. However, like conventional thyristors, they can only be turned off by reducing the conduction current to zero. Transistors, on the other hand, can be turned on and turned off by appropriate electrical inputs to the base electrode. Power transistors, however, are typically slower than thyristors.
It is the principal object of this invention to provide a fast switching transistor.
The invention resides in light-activated semiconductor switch comprising: a semiconductor body having a second impurity region disposed between and forming PN junctions with first and third impurity regions, said first region having higher resistivity than said first and said second impurity regions; a first electrode coupled to said first impurity region; and second electrode coupled to said third impurity region.
A light-activated semiconductor switch comprises a first coupling means for coupling the switch in a circuit and for facilitating current flow between the switch and the circuit, which first coupling means includes means for admitting electromagnetic radiation therethrough. A first region in a semiconductor body having a first type of conductivity in response to radiation admitted through the first coupling means for absorbing photons therefrom and thereby creating electron-hole pairs in the first region. A lightly doped second region in the semiconductor
body having a second type of conductivity is adjacent to the first region and forms a p-n junction therewith.
A heavily doped third region in the semiconductor body having the same second-type conductivity as the second region is adjacent thereto and facilitates ohmic contact between the second region and a second coupling means disposed on the third semiconductor region.
More particularly, in a preferred embodiment, a metal grid emitter electrode ohmically contacts the surface of the p region in a p-i-n (p-n#-n+) rectifier. A collector electrode which may be a metal grid structure is disposed on the surface of the n region (n+).
When the p-n junction in the switch is electrically reverse biased, a depletion region is formed and an electric field is created in the semiconductor body.
When light passes through the emitter grid and impinges upon the p region, electron-hole pairs are created in the depleted region thereby causing a drift current to flow in the external circuit. Even though the strength of the electric field in the semiconductor body decreases in direct proportion to the intensity of the light impinging upon the p region when the device is in series with a load resistance, the low doping or impurity concentration of the i(n) region ensures that an electric field continues to exist over most of the absorption volume (depletion region) in order to provide electron current flow in the external circuit.
The invention will become more readily apparent
from the following exemplary description in context
with the accompanying drawings, in which:
Figure 1 is a sectional view of a light-activated
semiconductor switch according to the present
invention;
Figure 2 shows a top view of the emitter electrode
grid referred to in Figure 1;
Figure 3 is a graph of the magnitude of the electric
field in the semiconductor crystal shown in Figure 1;
Figure 4 is an alternative embodiment of the
present invention wherein the collector electrode
has a grid structure;
Figure 5 is an alternative embodiment of the
present invention having semiconductor regions of conductivity type opposite that shown in Figure 1.
Figure 1 shows a sectional view of a p-i-n silicon
body 10 in accordance with the teachings of the present invention. The body 10 is comprised of
layers or regions 14, 15, and 16. Region 14 is a p-type
region approximately 25 Fm thick which is doped with any suitable substance which provides acceptor atoms, for example, boron, aluminum, or gallium.
The dopant or impurity concentration is preferably such that the region 14 is a p+ region, for example greater than 1016 acceptor atoms/cm3 and preferably 1018 to 1021 atoms/cm33. The p+ doping is preferred since it provides for a steeper slope in the electric field distribution as later discussed herein with reference to Figure 3. Since the slope of the electric field distribution is steeper in such a p + region, a thinner region can be used. Region 15 is an i or n type region approximately 450 lim thick lightly doped with any suitable substance which provides donor atoms, for example, phosphorus, antimony, or arsenic, such that the impurity or dopant concentration is effective to provide an n region, for
example, less than 1016 donor atoms/cm3 and preferably about 1014 atoms/cm3.The slope of the electric field distribution when the p-n junction is reverse biased, is directly proportional to the level of doping or impurity concentration therein. It is desirable, according to the teaching of the present invention, to provide an n region 15 having a low impurity concentration in order to effect an electric field distribution across the region 15 having a slow rate of decrease (shallow slope) as later discussed herein with reference to Figure 3. The p region 14 and the n region 16 from p-n junction 18.Region 16 is an n-type region approximately 25 Fm thick heavily doped with, for example, any substance
hereinbefore mentioned as suitable for doping the n region 15, such that the impurity or dopant concentration is effective to provide an n+ region, for example, greater than 1016 donor atoms/cm3. It is desirable according to the teachings of the present invention to provide an n+ region 16 having a heavy doping or impurity concentration in order to facilitate ohmic contact between the n region 15 and a metal collector electrode 22 disposed on a surface of the region or layer 16. A gridded emitter electrode 24 is disposed on a surface of the p region or layer 14 so that electromagnetic radiation or light is allowed to impinge upon the p region 14 through the openings in the emitter electrode 24.The emitter electrode 24 can be formed in any conventional manner such as depositing a layer of metal over the entire surface of the p region 14 and using a photo resist method to etch away the desired portions.
A top view of the emitter electrode 24 suitable for use in accordance with the teachings of the present invention is shown in Figure 2 wherein a layer of metal includes a conducting area 40 approximately 2 cm long and 2.5 mm wide. Electrode fingers 411 through 41n extend from the conducting area 40 and are each approximately 2 cm long and 2.5 mm wide.
The variable n represents the total number of electrode fingers extending from the conducting area 40. Gaps 431 through 43n-1 between the electrode fingers are approximately .5 mm wide but in any case must be no narrower than the wavelength of the light or electromagnetic radiation 55 to which it is desired that the switch respond. The variable n in this case is 267.
Figure 1 will be used to describe the operation of the switch of the present invention. The emitter electrode 24 is coupled to a terminal 30 of a resistor 31 by an electrical conductor 32. Aterminal 33 of the resistor 31 is coupled to an electrical conductor 34 to a negative terminal 37 of the power supply 36 is coupled by an electrical conductor 38 to the collector electrode 22. The power supply 36 causes the p-n junction 18to become reverse or back biased and a depletion region is formed which extends partially into the p-region 14, throughout the n region 15, and partially into the n+ region 16. An electric field E is created in the depletion region the magnitude distribution of which is shown in Figure 3 by the curve portions 52, 53 and 54.In Figure 3, an axis 50 is a measure of the magnitude of the electric field E and an axis 51 is a locus of distance points through the regions 14, 15 and 16. The magnitude ofthe electric field E rises rapidly in the depleted portion of the p region as depicted by the curve portion 52. This rapid rise in magnitude (steep slope) is eue to the heavy doping concentration in the P+ region 14. The magnitude of the electric field decreases through the n region 15 as shown by a curve portion 53.
However, the slope of curve portion 53 is determined by the doping concentration of the region 15 as hereinbefore discussed. The low doping concentration of the region 15 provides for a shallow slope of the curve portion 53. The magnitude of the electric field decreases rapidly (steep negative slope ) in the depleted portion of the n+ region 16 as shown by a curve portion 54 due to the heavy doping concentra
tion therein. When no light is impinging upon the p
region 14, the switch is said to be in the blocking
state and no current flows in the external circuit
through the resistor 31 since the semiconductor
body 10 is depleted of free electrons.
When light from a source denoted as 55 of
sufficiently short wavelength or sufficient intensity
impinges upon the p region 14, preferably at the
Brewster angle, most of the photons are created in
the high electric field region as shown in Figure 3,
creating electron-hole pairs. The phenomenon of
photon or optical absorption is old in the electrical
arts. It has been determined that 11,500 is the maximum wavelength or energy of light at which
electron-hole pairs can be created in silicon (which
has a band gap of 1.1 eV) by photon absorption. The voltage across the switch, i.e., the potential differ
ence between the conductors 32 and 38, decreases since free electrons are being created thereby caus
ing current to flow in the resistor 31.The holes created will recombine at p-n junction 18 while the electrons created (free electrons) will be swept out through the n-type regions 15 and 16 and flow around the circuit through the resistor 31 in order to
neutralize the hole current.
The magnitude of the electric field in the depleted region decreases as a result of the decrease in voltage across the switch hereinbefore discussed and is shown in Figure 3 by the curve portions 56,57 and 58. The n region 15 is effective to ensure that though a low voltage potential may exist across the switch, the slope of the curve portion 57 is shallow so that a finite magnitude of electric field is maintained in order to continue to propel the free electron created by photon absorption through the external circuit thereby maintaining current flow in the external circuit.
When the light 55 is removed, the switch will revert to the blocking state when the electrons and holes are swept out of the depletion region by the electric field. There will be some residual current due to stored charge in the non-depleted portions of the p region 14 and then region 16 which then diffuses into the depletion region after the light 55 is removed. In order to minimize this residual current, the p region 14 and then region 16 should be as narrow as possible and of low life-time. Present technology can provide thicknesses as narrow as 25cm, but the regions 14 and 16 should be no thicker than about 50 ym in order to minimize the deleterious effect of stored charge therein.
The power gain G of a switch according to the present invention can be written as: G = n Vs
Vp where: n = the quantum efficiency
Vs = blocking (system) voltage
Vp = photon voltage
It will be appreciated by those skilled in the art that the scope of the present invention is not limited by the details of the foregoing description ar;d that the present invention may be carried out in various ways and may take various forms and embodiments other than the illustrative embodiment hereinbefore de scribed. Figure 4, for example, shows an embodiment of the present invention similar to that shown in Figure 1 and wherein like characters refer to similar elements.A switch according to the present invention includes the semiconductor body 10 and a collector electrode 122 having a grid structure for allowing light or other electromagnetic energy to pass therethrough and impinge upon the n+ region 16. An emitter electrode 114 comprises a layer of metal having no holes or grid for admitting light.
Other possible embodiments would include, for example, a switch according to the present invention wherein both the collector and the emitter electrodes include means for allowing light to impinge upon the semi-conductor region upon which it is disposed.
Regions of conductivity type opposite that of regions 14,15 and 16 as shown in Figure 1 can be used. Such an embodiment is shown in Figure 5 wherein like characters refer to similar elements. In addition, the electrode 24 can be realized in any number of various ways and forms so long as the desired wavelength of electromagnetic radiation can impinge upon the region 14 according to the teachings of the present invention. These variations are not meant to be exhaustive nor are they meant to limit the scope of the present invention in any substantive way.
Claims (5)
1. A light-activated semiconductor switch comprising: a semiconductor body having a second impurity region disposed between and forming PN junctions with first and third impurity regions, said first region having a higher resistivity than said first and said second impurity regions; a first electrode coupled to said first impurity region, and a second electrode coupled to said third impurity region.
2. A switch according to claim 1 wherein said third semiconductor region has an impurity concentration between 1016 and 1021 acceptor atoms/cm3, the impurity concentration of the second region is between 1014 and 1016 donor atoms/cm3, and the impurity concentration of the third region is between 1016 and 1021 donor atoms/cm3.
3. A switch according to claims 1 or 2 wherein said second and third region have a thickness substantially thinner than said first region.
4. A switch according to claim 3 wherein said thickness of said first and third regions are each no more than 501lem.
5. A switch according to claim 4 wherein said thickness of said first and third regions is between 25 and 50 Fm.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US95242978A | 1978-10-18 | 1978-10-18 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2034518A true GB2034518A (en) | 1980-06-04 |
| GB2034518B GB2034518B (en) | 1983-06-29 |
Family
ID=25492902
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7935971A Expired GB2034518B (en) | 1978-10-18 | 1979-10-16 | Light activated p-i-n switch |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS5558582A (en) |
| BE (1) | BE879496A (en) |
| BR (1) | BR7906725A (en) |
| CA (1) | CA1157136A (en) |
| DE (1) | DE2942159A1 (en) |
| FR (1) | FR2439479A1 (en) |
| GB (1) | GB2034518B (en) |
| IN (1) | IN151851B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2127221A (en) * | 1982-09-06 | 1984-04-04 | Secr Defence | Radiation-controlled electrical switches |
| US4684972A (en) * | 1981-08-07 | 1987-08-04 | The British Petroleum Company, P.L.C. | Non-volatile amorphous semiconductor memory device utilizing a forming voltage |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57132471U (en) * | 1981-02-10 | 1982-08-18 | ||
| DD227311A1 (en) * | 1984-09-17 | 1985-09-11 | Adw Ddr | OPTOELECTRONIC SOLID BODY SWITCH |
| DE3715674A1 (en) * | 1987-05-11 | 1988-12-01 | Messerschmitt Boelkow Blohm | SEMICONDUCTOR WITH CAPACITIVE READING OF THE CARGO CARRIERS AND INTEGRATED DC VOLTAGE SUPPLY |
| US4782222A (en) * | 1987-09-03 | 1988-11-01 | Power Spectra | Bulk avalanche semiconductor switch using partial light penetration and inducing field compression |
| CN108039363A (en) * | 2017-11-30 | 2018-05-15 | 电子科技大学 | Optical drive SiC/GaN based semiconductor devices and its manufacture craft |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3424910A (en) * | 1965-04-19 | 1969-01-28 | Hughes Aircraft Co | Switching circuit using a two-carrier negative resistance device |
| GB1072080A (en) * | 1965-12-31 | 1967-06-14 | Standard Telephones Cables Ltd | Improvements in or relating to semiconductor devices |
-
1979
- 1979-10-16 GB GB7935971A patent/GB2034518B/en not_active Expired
- 1979-10-17 FR FR7925786A patent/FR2439479A1/en active Granted
- 1979-10-17 CA CA000337859A patent/CA1157136A/en not_active Expired
- 1979-10-18 DE DE19792942159 patent/DE2942159A1/en not_active Ceased
- 1979-10-18 BE BE0/197712A patent/BE879496A/en not_active IP Right Cessation
- 1979-10-18 JP JP13367479A patent/JPS5558582A/en active Pending
- 1979-10-18 BR BR7906725A patent/BR7906725A/en unknown
- 1979-10-19 IN IN1093/CAL/79A patent/IN151851B/en unknown
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4684972A (en) * | 1981-08-07 | 1987-08-04 | The British Petroleum Company, P.L.C. | Non-volatile amorphous semiconductor memory device utilizing a forming voltage |
| GB2127221A (en) * | 1982-09-06 | 1984-04-04 | Secr Defence | Radiation-controlled electrical switches |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2034518B (en) | 1983-06-29 |
| FR2439479B1 (en) | 1985-03-01 |
| DE2942159A1 (en) | 1980-04-30 |
| BE879496A (en) | 1980-04-18 |
| BR7906725A (en) | 1980-06-17 |
| FR2439479A1 (en) | 1980-05-16 |
| IN151851B (en) | 1983-08-20 |
| CA1157136A (en) | 1983-11-15 |
| JPS5558582A (en) | 1980-05-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |