GB2029639A - Infra-red photodetectors - Google Patents
Infra-red photodetectors Download PDFInfo
- Publication number
- GB2029639A GB2029639A GB7835913A GB7835913A GB2029639A GB 2029639 A GB2029639 A GB 2029639A GB 7835913 A GB7835913 A GB 7835913A GB 7835913 A GB7835913 A GB 7835913A GB 2029639 A GB2029639 A GB 2029639A
- Authority
- GB
- United Kingdom
- Prior art keywords
- layer
- junction
- diode
- conductivity type
- band gap
- 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.)
- Withdrawn
Links
- 239000000463 material Substances 0.000 claims abstract description 15
- 238000009792 diffusion process Methods 0.000 claims description 4
- 239000002019 doping agent Substances 0.000 claims description 4
- 229910052793 cadmium Inorganic materials 0.000 claims description 2
- 229910052749 magnesium Inorganic materials 0.000 claims description 2
- 229910052725 zinc Inorganic materials 0.000 claims description 2
- 229910000530 Gallium indium arsenide Inorganic materials 0.000 claims 1
- GPXJNWSHGFTCBW-UHFFFAOYSA-N Indium phosphide Chemical compound [In]#P GPXJNWSHGFTCBW-UHFFFAOYSA-N 0.000 claims 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims 1
- KXNLCSXBJCPWGL-UHFFFAOYSA-N [Ga].[As].[In] Chemical compound [Ga].[As].[In] KXNLCSXBJCPWGL-UHFFFAOYSA-N 0.000 claims 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 claims 1
- 239000011777 magnesium Substances 0.000 claims 1
- 239000011701 zinc Substances 0.000 claims 1
- 239000000969 carrier Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 239000004065 semiconductor Substances 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 230000015556 catabolic process Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910052732 germanium Inorganic materials 0.000 description 2
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 125000005842 heteroatom Chemical group 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 239000011533 mixed conductor Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 238000005036 potential barrier Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000006798 recombination Effects 0.000 description 1
- 238000005215 recombination Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000000927 vapour-phase epitaxy Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
- H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by at least one potential-jump barrier or surface barrier, e.g. phototransistors
- H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
- H01L31/102—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier
- H01L31/107—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier the potential barrier working in avalanche mode, e.g. avalanche photodiode
- H01L31/1075—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier the potential barrier working in avalanche mode, e.g. avalanche photodiode in which the active layers, e.g. absorption or multiplication layers, form an heterostructure, e.g. SAM structure
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
- H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by at least one potential-jump barrier or surface barrier, e.g. phototransistors
- H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
- H01L31/102—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier
- H01L31/109—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier the potential barrier being of the PN heterojunction type
Abstract
In a heterojunction photodetector diode, the detecting p-n junction 3 terminates at its circumference in material having a higher band-gap than that of the junction region. The main part of the p-n junction 3 is contained wholly within the material 1 of lower band-gap. <IMAGE>
Description
SPECIFICATION
Infra-red photodetectors
This invention relates to heterojunction photodetectors for infra-red transmissions.
There is increasing interest in the 1-1.6 .016m infra-red band, because of its superior propagation characteristics in optical fibre waveguide (1.0-1.4 urn), and its eye-safe characteristics (1.4-1.6 urn band). Considerable success has been achieved in making practical semiconductor laser sources for this band and it is becoming necessary to consider the development of suitable optical detectors. Conventional Si detectors, including both normal and avalanche photodiodes, have rapidly decreasing quantum efficiency at wavelengths beyond 1 um and are not satisfactory.Germanium detectors have optimum quantum efficiency at 1.5 um. Germanium photodiodes have been reported which are reasonably satisfactory in the vincinity ofthis wavelength butsufferfrom high dark current and high multiplication noise (due to comparable ionization rate of both carrier types). Optical detectors made from mixed conductors, such as three-or four-component
Ill-V compounds, with band gap tailored for the wavelength concerned, can provide considerably superior performance.
A particular advantage of the mixed semiconductors is that the band gap may be adjusted to be only justsmallerthan is necessary to absorb the radiation of the wavelength concerned, so that the lowest possible equilibrium concentration of minority carriers is present and the dark current is minimized. A second advantage is that in general the IIl-V Materials have unequal ionization coefficients for electrons and holes, which reduces multiplication noise in avalanche photodiodes. A third advantage is that it is possible to incorporate heterostructure layers of different composition of semiconductor into the device.This allows transparent windows to be made to improve photon collection efficiency, and potential barriers to be provided which improve the collection of photogenerated carriers (eliminating delayed collection) and can in principle reduce the volume from which thermally generated carriers are collected and hence further reduce dark current.
One problem which is encountered with such devices is the presence of leakage current at the boundary of the detecting p-n junction.
According to the present invention there is provided a heterojunction photodetector diode in which the detecting p-n junction terminates at its circumference in material having a higher band-gap than that of the junction region.
This conveniently provides a guard ring structure with higher reverse breakdown for stabilization of the avalanche operation and also contributes to a reduction in surface leakage current.
Embodiments of the invention will now be described with reference to the accompanying drawings, in which :- Figure 1 illustrates a cross-section of one form of infra-red photodetector diode, and
Figure2 illustrates a cross-section through a second form of infra-red photodetector diode.
A variety of mixed semiconductor materials are available with bandgaps in the required range including particularly the Il-IV and the Ill-V compounds. Most experience has been obtained to date with the Ill-V compounds and they have proved practical for the construction of lasers, photocathodes and optical detectors. Of these materials the band-gap requirement in the present instance limits the choice to the (Galn) (AsP) and the (GaAI) (AsSb) systems. The former system is in general the more versatile. It has been grown by vapour phase epitaxy as well as by liquid phase (in contrast to (GaAI) (AsSb)) and it shows no signs of solid imiscibility that is evident for some compositions of (GaAI) (AsSb).It can provide the good lattice match required at the interfaces between layers in heteros tructure devices over a useful range of composition when grown on an InP substrate. By approximate choice of the composition the detector can be designed to operate with maximum efficiency over a band of wavelengths anywhere in the range 1.0 - 1.6 urn.
The photodetector diode structure which will be described both contain a layer 1 of p-doped (Galn) (AsP) about 1 - 2 urn thick where the majority of the incident photons are absorbed and were the minority electrons are generated. The layer is backed, on the side of the light input, by a layer 2 of the p-type
InP that provides both a transparent window to the photons concerned and also an interface with the (Galn) (AsP) that has a lower minority carrier recombination velocity than would occur at a free surface.
The p-n junction 3 at the boundary of the p-type (GaIn) (AsP) where the minority carriers are detected is formed within a thicker (Galn) (AsP) layer 4 by diffusion of the p-type dopant (Zn, Mg or Cd) either during growth, as for the structure in Figure 1, or during a subsequent diffusion stage, as for the structure in Figure 2. The employment of a diffused junction ofthistype is difficult to avoid in (Galn) (AsP) because of the mobile nature of all the p-dopants. However, in this instance its occurrence is also particularly convenient since it results in the p-n junction being displaced from a grown boundary, where compostional changes (intentional or unintentional) and lattice mismatches are likely to occur into a region where there would be no such non-uniformities. Reverse bias leakage current at the p-n junction due to generation centres associated with misfit dislocations and other crystalline imperfections should therefore be minimized.
The p-n junction traverses some of the higher band-gap material 2 before reaching its outer boundary - the surface in the structure of Figure 2 or a proton bombarded region 4 in the structure of Figure 1. This modification reduces the reverse bias leakage current generated at either type of boundary. It also provides an outer guard ring to the active area of the p-n junction with a higher reverse breakdown voltage. The former effect reduces the dark current and the latter effect provides a safer outer boundary for operation of the detector under conditions of avalanche multiplication. Improvement along these lines is particularly significant for longer wavelength detectors.
Claims (6)
1. A heterojunction photodetector diode in which the detecting p-n junction terminates at its circumference in material having a higher band-gap than that of the junction region.
2. A diode according to claim 1 wherein a first layer of the higher band gap material overlays a second layer of a lower band gap material, both said layers being of the same conductivity type, and the detecting junction is formed by diffusion of a dopant material of the opposite conductivity type through the first layer and part way into the second layer, the diffusion being restricted to an area lying wholly within the boundary of the first layer.
3. A diode according to claim 1 wherein a first layer of the higher band gap material overlays a second layer of a lower band gap material, both of which are of the same conductivity type, and the whole of the first layer and an adjoining region of the second layer are both doped with a material of the opposite conductivity type, and an annular region of the first and second layers is formed into a guardring structure by proton bombardment.
4. A diode structure according to claim 2 or 3 wherein the first layer in n-type Indium Phosphide the second layer in n-type Indium Gallium - Arsenide
Phosphide.
5. A diode according to claim 4 wherein the dopant material is Zinc, Magnesium or Cadmium.
6. A heterojunction photodetector diode substantially as described with reference to either Figure 1 or Figure 2 of the accompanying drawing.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7835913A GB2029639A (en) | 1978-09-07 | 1978-09-07 | Infra-red photodetectors |
| JP11506979A JPS5555583A (en) | 1978-09-07 | 1979-09-07 | Hetero junction photodetecting diode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7835913A GB2029639A (en) | 1978-09-07 | 1978-09-07 | Infra-red photodetectors |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2029639A true GB2029639A (en) | 1980-03-19 |
Family
ID=10499500
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7835913A Withdrawn GB2029639A (en) | 1978-09-07 | 1978-09-07 | Infra-red photodetectors |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS5555583A (en) |
| GB (1) | GB2029639A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2482386A1 (en) * | 1980-03-31 | 1981-11-13 | Nippon Telegraph & Telephone | OPTO-ELECTRONIC CONTACTOR |
| GB2145283A (en) * | 1983-08-18 | 1985-03-20 | Standard Telephones Cables Ltd | Photodetector |
| FR2556883A1 (en) * | 1983-12-14 | 1985-06-21 | Thomson Csf | Photoconductor device having a high gain-band product. |
| FR2592740A1 (en) * | 1986-01-08 | 1987-07-10 | Commissariat Energie Atomique | HETEROJUNCTION HGCDTE PHOTOVOLTAIC DETECTOR AND MANUFACTURING METHOD THEREOF |
| US4887138A (en) * | 1988-03-23 | 1989-12-12 | The United States Of America As Represented By The Secetary Of The Air Force | P-I-N photodetector having a burried junction |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5051285A (en) * | 1973-09-05 | 1975-05-08 | ||
| JPS5231690A (en) * | 1975-09-04 | 1977-03-10 | Fujitsu Ltd | Productin method of semiconductor device |
| JPS5399889A (en) * | 1977-02-14 | 1978-08-31 | Nippon Telegr & Teleph Corp <Ntt> | Composite photo detector |
-
1978
- 1978-09-07 GB GB7835913A patent/GB2029639A/en not_active Withdrawn
-
1979
- 1979-09-07 JP JP11506979A patent/JPS5555583A/en active Pending
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2482386A1 (en) * | 1980-03-31 | 1981-11-13 | Nippon Telegraph & Telephone | OPTO-ELECTRONIC CONTACTOR |
| GB2145283A (en) * | 1983-08-18 | 1985-03-20 | Standard Telephones Cables Ltd | Photodetector |
| EP0135313A2 (en) * | 1983-08-18 | 1985-03-27 | Stc Plc | Photodetector |
| EP0135313A3 (en) * | 1983-08-18 | 1986-07-30 | Stc Plc | Photodetector |
| US4625226A (en) * | 1983-08-18 | 1986-11-25 | Standard Telephones And Cables Public Limited Company | Photodetector |
| FR2556883A1 (en) * | 1983-12-14 | 1985-06-21 | Thomson Csf | Photoconductor device having a high gain-band product. |
| FR2592740A1 (en) * | 1986-01-08 | 1987-07-10 | Commissariat Energie Atomique | HETEROJUNCTION HGCDTE PHOTOVOLTAIC DETECTOR AND MANUFACTURING METHOD THEREOF |
| EP0229574A1 (en) * | 1986-01-08 | 1987-07-22 | Commissariat A L'energie Atomique | Photovoltaic HgCdTe heterojunction detector, and method for its production |
| US4791467A (en) * | 1986-01-08 | 1988-12-13 | Commissariat A L'energie Atomique | Heterojunction HgCdTe photovoltaic detector and its production process |
| US4887138A (en) * | 1988-03-23 | 1989-12-12 | The United States Of America As Represented By The Secetary Of The Air Force | P-I-N photodetector having a burried junction |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5555583A (en) | 1980-04-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |