GB2053567A - Photodiode - Google Patents
Photodiode Download PDFInfo
- Publication number
- GB2053567A GB2053567A GB8021862A GB8021862A GB2053567A GB 2053567 A GB2053567 A GB 2053567A GB 8021862 A GB8021862 A GB 8021862A GB 8021862 A GB8021862 A GB 8021862A GB 2053567 A GB2053567 A GB 2053567A
- Authority
- GB
- United Kingdom
- Prior art keywords
- photodiode
- absorption layer
- diode
- region
- semiconductor
- 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- Withdrawn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
- 238000010521 absorption reaction Methods 0.000 claims abstract description 28
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 4
- 229910008310 Si—Ge Inorganic materials 0.000 claims abstract 2
- 239000004065 semiconductor Substances 0.000 claims description 33
- 239000000463 material Substances 0.000 claims description 24
- 229910052732 germanium Inorganic materials 0.000 claims description 6
- 229910001218 Gallium arsenide Inorganic materials 0.000 claims description 4
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical group [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 claims description 4
- 230000005684 electric field Effects 0.000 claims description 2
- 230000004888 barrier function Effects 0.000 abstract 3
- 230000005855 radiation Effects 0.000 description 5
- 238000000151 deposition Methods 0.000 description 3
- 238000005286 illumination Methods 0.000 description 3
- 238000000407 epitaxy Methods 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 229910000676 Si alloy Inorganic materials 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000002800 charge carrier Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 238000004020 luminiscence type Methods 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 230000007704 transition Effects 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 potential barriers, e.g. phototransistors
- H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
- H01L31/11—Devices sensitive to infrared, visible or ultraviolet radiation characterised by two potential barriers, e.g. bipolar phototransistors
-
- 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 potential barriers, 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
- H01L31/103—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier the potential barrier being of the PN homojunction type
-
- 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 potential barriers, 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
- H01L31/107—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier the potential barrier working in avalanche mode, e.g. avalanche photodiodes
- H01L31/1075—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier the potential barrier working in avalanche mode, e.g. avalanche photodiodes in which the active layers, e.g. absorption or multiplication layers, form an heterostructure, e.g. SAM structure
Landscapes
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Light Receiving Elements (AREA)
Abstract
In a photo-diode containing a rectifying barrier (a PN-junction or a metal-s.c. junction) an absorption layer (p-Ge) is provided, having the same conductivity type as, but of a smaller band gap than, the conductivity type and the bend gap respectively of the adjacent s.c. layer forming the rectifying barrier. Typically, the s.c. layer of the rectifying barrier is of Si, Ga, As or InP and the absorption layer is of Ge intermediate Si-Ge layers may be provided to accommodate mismatch between the s.c. layer and the absorption layer. <IMAGE>
Description
SPECIFICATION
Photodiode
The present invention relates to photodiodes as are used, for example, for receivers in optical communication systems, and in particular to the category of photodiodes that are commonly termed p.i.n. diodes in order to distinguish them from the category of photodiodes designed to operate under avalanche conditions.
Fundamental problems and designs of photodiodes are described in various publications (e.g. H. Melchior, "Sensitive High-Speed
Photodetectors for the Demodulation of Visible and Near Infrared Light"; Journal of Luminescence 7 (1973), pp. 390-414; S. Metz, "Eigenschaften und Entwicklungsstendenzen schneller
Photodetektoren für die optische Nachrichten übertragung", NTZ, Vol. 29 (1976), No. 2, pp.
127-133).
Photodiodes are reverse-biased semiconductor devices with a pn junction or a semiconductormetal junction. The wavelength absorbed by the diode is smaller than or equal to the wavelength corresponding to the band gap of the semiconductor material used. However, the band gap determines not only the absorbable wavelengths but also, for example, the dark current, which greatly influences diode noise. The greater the band gap, the smaller the dark current will generally be. In view of the two dependences just described, one tries to choose a semiconductor material whose band gap is equal to or only slightly smaller than the energy of the quanta to be detected.
The glass fibres currently being used for tests in optical communications have attenuation minima at wavelengths around 1.2 4m and 1.6 ym.
However, semiconductors which absorb these wavelengths well have a small band gap and, consequently, a large thermal dark current and strong shot noise.
The semiconductor material mainly used for diodes with good reverse-bias characteristic, i.e., breakdown at high reverse voltages and low dark currents, i.e., with low shot noise, is Si.
An object of the invention is to design a photodiode having a pn junction or a metalsemiconductor junction with reverse-bias characteristic as the diode region in such a way that materials with good receiver characteristics, such as are used for prior art diodes, can be used irrespective of the wavelength of the radiation to be absorbed, such a material being Si, for example.
According to the present invention there is provided a photodiode having a rectifying region containing a pn junction, or a metalsemiconductor junction with reverse-bias characteristic, which region is bounded on one side by an absorbing layer of semiconductor material which has a smaller band gap than that of the adjacent semiconductor region of the the rectifying region and has the same conductivity type as that of said adjacent region.
Diodes according to the invention have many advantages. By depositing a strongly absorbing semiconductor layer upon the rectifying region, made for instance of silicon, the response of the photodiode can be matched in a simple manner to any wavelength to be received. This permits simple fabrication of optionally sensitive diodes for predetermined wavelength regions. Since the layers forming the pn junction, which influence the dark currents most, are made of semiconductor material with good rectifying characteristics, the quality of the absorption layer need no longer meet such stringent requirements.
The photodiodes according to the invention can also be used in monolithic circuits. Such circuits, frequently called ICs, are usually made from Si or
GaAs, which are both materials from which diodes as set forth in the preamble of the claim are fabricated, as is well known. By deposition of suitably absorbing semiconductors, the wavelengths to be received best can be set in the integrated circuits.
Furthermore, the absorbing semiconductor materials used may be those from which no pn junctions can be formed directly, and which are, therefore, partly unsuitable for photodiodes as set forth in the preamble of the claim.
The invention will now be explained in more detail with reference to embodiments thereof and to the accompanying drawing.
The single figure of the drawing shows an embodiment of a photodiode according to the invention.
To fabricate the photodiode shown in the figure, a p-Si layer 5 to 100 4m in thickness is epitaxially grown on a n+Si substrate. On this layer is grown the layer of strongly absorbing semiconductor material, in this case p-Ge, e.g. by gas-phase epitaxy. The thickness of the germanium layer depends on the wavelength to be absorbed. At 1.2 Mm wavelength, the germanium layer is about 1.5 ,um thick; at 1.5 ,um wavelength, the layer thickness is about 10 ,um.
Finally, the diode is mesa-etched to the usual shape.
To produced ohmic contacts, Au-Ti contacts are evaporated on both sides. On the side of the n±Si, however, a "window" 1 is left open, through which the radiation S penetrates into the diode. During fabrication a large number of units are arranged in parallel on a common substrate, this multiple arrangement being referred to as a "wafer" in the Anglo-American literature. After the wafer has been separated into the individual diodes, the latter are placed on a gold base having an aperature 2, which is also designed to pass the radiation to the diode. At the aforementioned wavelengths of 1.2 Mm or 1.5 ym, Si is transparent. This means that the radiation to be absorbed passes through the Si-diode region unobstructed and is absorbed only in the germanium.
The semiconductor materials of the individual layers can be either elemental semiconductors, such as Ge or Si, or compound semiconductors, such as GaAs, InP, CdS or CulnSe2, or alloy semiconductors, such as Ga,, In, A51#y Py. The semiconductor material of the diode region should be present in the best possible crystalline form, because this guarantees low leakage currents and, hence, low diode noise. By contrast, the absorption layer may be of a lower crystal quality and even polycrystalline or amorphous.
Instead of the pn junction in the diode region, a metal-semiconductor junction, e.g. Au to p-Si, may be used.
The diode in the embodiment described rs intended to be illuminated through the diode region. If a window is provided in the contact layer on the absorption layer, it is, of course, also possible to illuminate the diode through the absorption layer, which may be advantageous if the light is already absorbed by the semiconductor material of the diode region. Illumination from the side through the absorption layer is especially advantageous if very long wavelengths are to be received, which are absorbed very weakly by certain semiconductors such as those involving absorption by indirect transitions.Through the later illumination, the effective absorption length is equal to the lateral extension of the absorption layer, not to the layer thickness, and can thus be made very large without increasing the carrier drift transit time from the absorption layer to the diode region.
To accommodate the difference in the lattice constants of the semicondutor materials of the diode region and the absorption region, intermediate layers can be used, e.g. Ge-Si intermediate layers. If Si is used in the diode region, the absorption layer may also be a Ge-Si alloy in order to achieve wavelength matching, which results in smaller dark currents, and a reduction of the lattice mismatch in one step.
The semiconductor of the absorption layer should be doped only so heavily that the field set up upon application of the reverse voltage reaches into the absorption layer to the point that most of the incident light is absorbed in the area of the electric field. By depositing a heavily doped region on the lower doped absorption layer, the field distribution can be controlled so that the charge carriers throughout the absorption layer reach the saturation drift velocity. This is especially important for high-speed diodes. The measures are commonly used in avalanche photodiodes and described in detail, for example, in an articles by L. J. M. Bollen et al, "Die Avalanche
Fotodiode", Philips techn. Rdsch. 36, 1976,77,
No. 7. pp. 220-226.
Instead of only one semiconductor material, different semiconductor materials with different band gaps may be deposited as an absorption layer on the diode region side by side so that several wavelengths can be received with one diode. They are deposited, for example, by gasphase epitaxy, covering those portions of the diode region with masks on which the respective semiconductor material is not to grow. For illumination from the side, stripes are provided at whose ends the radiation can enter.
Claims (15)
1. A photo diode having a rectifying region containing a pn junction, or a metalsemiconductor junction with reverse-bias characteristic, which region is bounded on one side by an absorbing layer of semiconductor material which has a smaller band gap than that of the adjacent semiconductor region of the rectifying region and has the same conductivity type as that of said adjacent region.
2. A photodiode as claimed in claim 1 where the semiconductor material of the rectifying region is Si, GaAs, or In P.
3. A photodiode as claimed in claim 1 or 2 wherein the semiconductor material of the absorption layer is germanium, Ga,~,ln,As,,P,, Ga,~,ln,As, Ga,~xAixAs,~ySby, GaAs~xSbx or CuinSee.
4. A photodiode as claimed in claim 1, 2 or 3 wherein the lattice constants of the semiconductor materials of the absorption layer and of the diode region are matched substantially.
5. A photodiode as claimed in claim 1, 2, or 3 wherein the semiconductor materials of the rectifying region and the absorbing layer are respectively Si and Ge, and wherein the mismatch of lattice constants are accommodated by means of Si-Ge intermediate layers.
6. A photodiode as claimed in any preceding claim, wherein the diode is illuminated through the rectifying region.
7. A photodiode as claimed in any one of claims 1 to 5, wherein the diode is illuminated through the absorption layer.
8. A photodiode as claimed in any one of claims 1 to 5, wherein the diode is illuminated from the side.
9. A photodiode as claimed in any preceding claim, wherein the semiconductor material of the diode is monocrystalline.
10. A photodiode as claimed in any one of claims 1 to 8, wherein the absorption layer is polycrystalline or amorphous.
11. A photodiode as claimed in any preceding claim wherein the absorption layer is doped so that the field set up in the diode by the applied reverse voltage reaches into the absorption layer to the point that most of the incident light is absorbed in the area of the electric field.
12. A photodiode as claimed in claim 1 1, wherein a heavily doped region of the same conductivity type as that of the semiconductor of the absorption layer is deposited on the absorption layer.
13. A photodiode as claimed in any preceding claim wherein the absorption layer is made of several semiconductor materials deposited side by side and having different band gaps.
14. A photodiode substantially as hereinbefore described with reference to the accompanying drawing.
15. A photodiode as claimed in any preceding claim wherein the diode forms part of an integrated circuit.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19792927126 DE2927126A1 (en) | 1979-07-05 | 1979-07-05 | PHOTODIOD |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2053567A true GB2053567A (en) | 1981-02-04 |
Family
ID=6074945
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8021862A Withdrawn GB2053567A (en) | 1979-07-05 | 1980-07-03 | Photodiode |
Country Status (2)
| Country | Link |
|---|---|
| DE (1) | DE2927126A1 (en) |
| GB (1) | GB2053567A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2143373A (en) * | 1983-07-14 | 1985-02-06 | Philips Nv | Radiation-sensitive diode |
| EP0167305A2 (en) * | 1984-07-06 | 1986-01-08 | The Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britain and | Photodetector |
| GB2216716A (en) * | 1988-03-24 | 1989-10-11 | Nat Space Dev Agency | Infrared sensor |
| AT393009B (en) * | 1989-11-07 | 1991-07-25 | Poska Albertas Ionas Antanovic | AUTOMATIC VALVE |
| GB2240874A (en) * | 1990-02-10 | 1991-08-14 | Stc Plc | Photodiode |
| GB2383644A (en) * | 2001-12-27 | 2003-07-02 | Bookham Technology Plc | Integrated optical device with non-crystalline light absorbent regions |
-
1979
- 1979-07-05 DE DE19792927126 patent/DE2927126A1/en not_active Withdrawn
-
1980
- 1980-07-03 GB GB8021862A patent/GB2053567A/en not_active Withdrawn
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2143373A (en) * | 1983-07-14 | 1985-02-06 | Philips Nv | Radiation-sensitive diode |
| EP0167305A2 (en) * | 1984-07-06 | 1986-01-08 | The Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britain and | Photodetector |
| EP0167305A3 (en) * | 1984-07-06 | 1987-09-16 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And | Photodetector |
| US5016073A (en) * | 1984-07-06 | 1991-05-14 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland | Photodetector semiconductor which does not require extensive cooling |
| GB2216716A (en) * | 1988-03-24 | 1989-10-11 | Nat Space Dev Agency | Infrared sensor |
| US4939561A (en) * | 1988-03-24 | 1990-07-03 | National Space Development Agency Of Japan | Infrared sensor |
| GB2216716B (en) * | 1988-03-24 | 1992-07-15 | Nat Space Dev Agency | Infrared sensor |
| AT393009B (en) * | 1989-11-07 | 1991-07-25 | Poska Albertas Ionas Antanovic | AUTOMATIC VALVE |
| GB2240874A (en) * | 1990-02-10 | 1991-08-14 | Stc Plc | Photodiode |
| GB2240874B (en) * | 1990-02-10 | 1993-07-07 | Stc Plc | Photodiode |
| GB2383644A (en) * | 2001-12-27 | 2003-07-02 | Bookham Technology Plc | Integrated optical device with non-crystalline light absorbent regions |
Also Published As
| Publication number | Publication date |
|---|---|
| DE2927126A1 (en) | 1981-01-08 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6384462B1 (en) | Planar hetero-interface photodetector | |
| CA2050362C (en) | Photo-sensing device | |
| US4875084A (en) | Optoelectric transducer | |
| US4656494A (en) | Avalanche multiplication photodiode having a buried structure | |
| US4814847A (en) | Ingaas semiconductor structures | |
| US4761383A (en) | Method of manufacturing avalanche photo diode | |
| Eden | Heterojunction III—V alloy photodetectors for high-sensitivity 1.06-µm optical receivers | |
| US5663075A (en) | Method of fabricating backside illuminated FET optical receiver with gallium arsenide species | |
| EP0452801B1 (en) | Semiconductor device having light receiving element and method of producing the same | |
| US3371213A (en) | Epitaxially immersed lens and photodetectors and methods of making same | |
| US4608586A (en) | Back-illuminated photodiode with a wide bandgap cap layer | |
| US4183035A (en) | Inverted heterojunction photodiode | |
| US4110778A (en) | Narrow-band inverted homo-heterojunction avalanche photodiode | |
| US5315148A (en) | Photo-sensing device | |
| GB2053567A (en) | Photodiode | |
| US4544938A (en) | Wavelength-selective photodetector | |
| EP0304048A2 (en) | A planar type heterostructure avalanche photodiode | |
| US4729963A (en) | Fabrication method for modified planar semiconductor structures | |
| EP0522746B1 (en) | Semiconductor photodetector device | |
| US8963274B2 (en) | Epitaxial structure for vertically integrated charge transfer gate technology in optoelectronic materials | |
| JPS6244709B2 (en) | ||
| US3436549A (en) | P-n photocell epitaxially deposited on transparent substrate and method for making same | |
| GB2206998A (en) | Avalanche photodetector | |
| US11894480B2 (en) | Low leakage current germanium-on-silicon photo-devices | |
| US4162203A (en) | Method of making a narrow-band inverted homo-heterojunction avalanche photodiode |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |