CN101221995A - Multi-layer sensitive film optical cavity structure Schottky barrier infrared detector - Google Patents

Abstract

The invention discloses a Schottky barrier infrared detector with a multi-layer sensitive membrane optical cavity structure which comprises a metal reflection mirror, optical cavity medium, silicide sensitive membranes, an N type protection ring, an N+ electrode, a P+ electrode, a P type substrate and an anti-reflection membrane. The invention is characterized in that: a plurality of layers of silicide sensitive membranes can be arranged; P type amorphous silicon is clamped between each two silicide sensitive membranes and between the silicide sensitive membranes and the optical cavity medium, the silicide sensitive membranes are all connected with the N type protection ring. The invention selects a three-layer silicide sensitive membrane structure as a preferred structure, upper surfaces and lower surfaces of the silicide sensitive membranes are all made of silicon, hot holes which experiences a plurality of scatterings and can meet the condition of being injected into the silicon can be injected into the silicon, the probability that the hot holes are injected into the silicon is almost increased by 1 fold or so compared with the conventional structure. The invention has the advantages that: the invention can improve the photoelectric conversion efficiency by more than 3 times than the conventional Schottky barrier infrared detector, and the production process is compatible with the production process of the conventional Schottky barrier infrared detector.

Description

The multi-layer sensitive film optical cavity structure Schottky barrier Infrared Detectors

Technical field

The present invention relates to a kind of optical cavity structure Schottky barrier infrared detector, relate in particular to a kind of multi-layer sensitive film optical cavity structure Schottky barrier Infrared Detectors.

Background technology

As far back as the eighties of last century early forties, the photoelectric type Infrared Detectors has just come out, and five, the correlative study of sixties Schottky barrier infrared detector just begun; 1973, the F.D.Shepherd in air research center, Rome and A.C.Yang just proposed silicide Schottky barrier infrared detector focal plane array notion; In 1975～1979 years, just reported the infrared palladium silicon of the Schottky barrier of making (Pd by documents such as E.S.Kohn and S.A.Rooslid ₂Si) or platinum silicon (PtSi) detector sensitive membrane thickness be about 60nm, the photoresponse rate of detector is relatively low, is 0.1% to 4 mum wavelength platinum silicon Schotty barrier infrared detector infrared electro conversion efficiencies; By 1980, R.W.Taylor and W.F.Kosonocky etc. have just reported, infrared palladium silicon of Schottky barrier or the PtSi detector sensitive membrane thickness made are 2～10nm, detector has optical cavity structure, the thick sensitive membrane detector that photoresponse efficient is made in earlier stage improves about 10 times, is 1% to 4 mum wavelength platinum silicon Schotty barrier infrared detector infrared electro conversion efficiencies; Nineteen eighty-two P.W.Pellegrini etc. has reported that again iridium silicon (IrSi) Schottky barrier infrared detector can be used for surveying 8～10 mum wavelength scope infrared lights.Up to the eighties of last century the nineties, the correlative study of Schottky barrier infrared detector has just had significant progress, the platinum silicon Schotty barrier infrared detector with optimization optical cavity structure of reports such as nineteen ninety W.F.Kosonocky, platinum silicon-sensitive film thickness is 2nm, is 1～2% to 4 mum wavelength infrared electro conversion efficiencies; Nineteen ninety-five T.L.Lin etc. report in platinum silicon/silicon interface growth skim (0.1～0.5nm) high concentration (10 ¹⁸～10 ²¹Cm ^-3) boron-dopped layer, platinum silicon Schotty barrier infrared detector cut-off wavelength is changed at 5.7～22 mu m ranges, improve near about 5 times of the photoelectric conversion efficiency of platinum silicon Schotty barrier infrared detector 5 μ m; In 2000 this century, the porous platinum silicon Schotty barrier infrared detector of report such as Farshi Raissi forms platinum silicon-sensitive film on porous silicon, and the Infrared Detectors photoelectric conversion efficiency can be greater than 10%.

But, porous platinum silicon Schotty barrier infrared detector is compared with conventional optical cavity structure Schottky barrier infrared detector, the sensitive membrane area of unit are increases greatly, improved the detector photoelectric conversion efficiency, but because of the porous silicon aperture is 2 μ m, hole depth is 8 μ m, makes uniform 20～40 μ m small unit size detector arrays of photoresponse and has difficulties.

In sum, Schottky barrier infrared detector grows out of nothing, from the lower-performance to the superior performance, go so far as the porous platinum silicon Schotty barrier infrared detector of present stage, wherein, conventional Schottky barrier infrared detector photoelectric conversion efficiency is low, though the conventional Schottky barrier infrared detector height of porous platinum silicon Schotty barrier infrared detector photoelectric conversion efficiency, but be difficult to make the small unit size detector array.

Summary of the invention

The invention provides a kind of photoelectric conversion efficiency height, the multi-layer sensitive film optical cavity structure Schottky barrier Infrared Detectors of manufacture craft and conventional Schottky barrier infrared detector compatibility.

Multi-layer sensitive film optical cavity structure Schottky barrier Infrared Detectors of the present invention, it comprises: metallic mirror, optical cavity medium, silicide sensitive membrane, N type guard ring, N+ electrode, P+ electrode, P type substrate and anti-reflective film is characterized in that: described silicide sensitive membrane can have multilayer; In twos between the silicide sensitive membrane and and the optical cavity medium between all accompany P type amorphous silicon; Each layer silicide sensitive membrane all is connected with N type guard ring.

Each layer silicide sensitive membrane is wrapped up therebetween P type amorphous silicon fully as a whole and is connected with N type guard ring; The optical cavity medium will top layer P type amorphous silicon and silicide sensitive membrane outer surface cover fully.

Described silicide sensitive membrane has three layers, then has three layers of P type amorphous silicon, and wherein two-layer P type amorphous silicon is clipped between three layers of silicide sensitive membrane, also has one deck P type amorphous silicon to cover on the silicide sensitive membrane of top layer.

The gross thickness of described three layers of silicide sensitive membrane and three layers of P type amorphous silicon is 5～25nm.

Described silicide sensitive membrane thickness is in 2nm.

Described P type amorphous silicon, its doping content is 10 ¹⁴～10 ¹⁷Cm ^-3

Described P type amorphous silicon, its doping content is 10 ¹⁸～10 ²¹Cm ^-3

Useful technique effect of the present invention is: photoelectric conversion efficiency can be brought up to more than 3 times of conventional Schottky barrier infrared detector, manufacture craft and conventional Schottky barrier infrared detector compatibility.

Description of drawings

Accompanying drawing 1, conventional Schottky barrier infrared detector structural representation;

2, three layers of Schottky barrier infrared detector structural representation of accompanying drawing;

Accompanying drawing 3, multilayer Schottky barrier infrared detector top view structural representation;

In the accompanying drawing: metallic mirror 1, optical cavity medium 2, silicide sensitive membrane 3, N type guard ring 4, P type substrate 5, P type amorphous silicon 6, anti-reflective film 7.

Embodiment

A kind of multi-layer sensitive film optical cavity structure Schottky barrier Infrared Detectors, it comprises: metallic mirror 1, optical cavity medium 2, silicide sensitive membrane 3, N type guard ring 4, N+ electrode, P+ electrode, P type substrate 5 and anti-reflective film 7 is characterized in that: described silicide sensitive membrane 3 can have multilayer; In twos 3 of silicide sensitive membrane and and 2 in optical cavity medium all accompany P type amorphous silicon 6; Each layer silicide sensitive membrane 3 all is connected with N type guard ring 4.

Each layer silicide sensitive membrane 3 is wrapped up therebetween P type amorphous silicon 6 fully as a whole and is connected with N type guard ring 4; Optical cavity medium 2 will top layer P type amorphous silicon 6 and silicide sensitive membrane 3 outer surfaces cover fully.

Described silicide sensitive membrane 3 has three layers, then has three layers of P type amorphous silicon 6, and wherein two-layer P type amorphous silicon 6 is clipped in 3 of three layers of silicide sensitive membrane, also has one deck P type amorphous silicon 6 to cover on the silicide sensitive membrane 3 of top layer.

The gross thickness of described three layers of silicide sensitive membrane 3 and three layers of P type amorphous silicon 6 is 5～25nm.

Described silicide sensitive membrane 3 thickness are in 2nm.

Described P type amorphous silicon 6, its doping content is 10 ¹⁴～10 ¹⁷Cm ^-3

Described P type amorphous silicon 6, its doping content is 10 ¹⁸～10 ²¹Cm ^-3

Multi-layer sensitive film optical cavity structure Schottky barrier Infrared Detectors of the present invention, selecting three layers of silicide sensitive membrane 3 structure for use is a kind of preferred structure that the present invention adopts.

The present invention mainly utilizes following two kinds of principles to improve the detector photoelectric conversion efficiency:

1) in the thin silicide sensitive membrane 3 hot hole in repeatedly scattering of suicide surfaces, the hot hole that light activated energy is higher than schottky barrier height increases principle by the probability that silicide layer injects silicon (opto-electronic conversion is finished thus): referring to conventional Schottky barrier infrared detector structural representation shown in the accompanying drawing 1, conventional optical cavity structure Schottky barrier infrared detector silicide sensitive membrane 3 is between optical cavity medium 2 and the P type substrate 5, satisfies the hot hole that injects silicon strip spare through scattering repeatedly and can't inject in silicide sensitive membrane 3 and 2 in optical cavity medium; Referring to three layers of Schottky barrier infrared detector structural representation shown in the accompanying drawing 2, multi-layer sensitive film optical cavity structure Schottky barrier Infrared Detectors silicide sensitive membrane 3 upper and lower surfaces of the present invention are silicon (silicon comprises P type substrate 5 and P type amorphous silicon 6) herein, satisfy the hot hole that injects silicon strip spare through scattering repeatedly and can inject silicon, the probability of comparing hot hole injection silicon with conventional structure increases about 1 times, makes the detector photoelectric conversion efficiency increase by 1 times.

2) the multiple coupling principle of absorption of 3 pairs of infrared lights of three layers of silicide sensitive membrane of optical cavity structure: because three layers of silicide sensitive membrane 3 and three layers of P type amorphous silicon 6 gross thickness are 5～25nm, be significantly smaller than optical cavity medium 2 thickness 500～900nm, it is effective therefore every layer of silicide sensitive membrane 3 all to be can be considered optical cavity; The transmitance that infrared light sees through the thin silicide sensitive membrane 3 (thickness is in 2nm) of platinum silicon is 45%, infrared light is 1 through ground floor silicide sensitive membrane 3 photoelectric conversion efficiencys thus, the second layer is 0.45, the 3rd layer is 0.2, consider the optical coupling effect between the photaesthesia rete, photoelectric conversion efficiency is greater than independent three layers of photaesthesia film photoelectric conversion efficiency sum 1.65.

Increase factor according to above-mentioned two photoelectric conversion efficiencys, three layers of sensitive film optical cavity structure Schottky barrier infrared detector photoelectric conversion efficiency of the present invention are 1 * 2+0.45 * 2+0.2 * 2=3.3, promptly are more than 3 times of conventional optical cavity structure Schottky barrier infrared detector photoelectric conversion rate.

In addition, between three layers of silicide sensitive membrane 3 and its top can make three layers of heavily doped P type amorphous silicon 6 thin layer, the Schottky barrier infrared detector cut-off wavelength is prolonged, change at 5.7～22 mu m ranges, improve near the photoelectric conversion efficiency of Schottky barrier infrared detector cut-off wavelength; P type amorphous silicon 6 thin layers that are complementary with three layers of silicide sensitive membrane 3 are if be made as common doping, and Schottky barrier infrared detector does not just have cut-off wavelength prolongation effect.

Conventional optical cavity structure Schottky barrier infrared detector operation principle:

Referring to conventional Schottky barrier infrared detector structural representation shown in the accompanying drawing 1, the part infrared light incides silicide sensitive membrane 3 by anti-reflective film 7 and is absorbed, the photon excitation photoproduction electron-hole pair that absorbs, energy greater than schottky barrier height and in momentum space the hole less than critical escape angle be injected in the P type substrate 5; In thin silicide sensitive membrane 3 and 5 of P type substrates and silicide sensitive membrane 3 and 2 repeatedly scatterings of optical cavity medium, angle change is less than still also injecting P type substrate 5 greater than the hole of schottky barrier height in critical escape angle and energy to part greater than the hole at critical escape angle; Injecting the hole of P type substrate 5 is collected by the P+ electrode, the corresponding clean electronics that stays is collected by the N+ electrode in silicide sensitive membrane 3 becomes useful signal, all the other electrons excited-holes are right, because energy was reduced to and is lower than schottky barrier height after the hole was repeatedly reflected, electronics and hole will be compound again.

Another part infrared light sees through thin silicide sensitive membrane 3 and returns thin silicide sensitive membrane 3 through optical cavity medium 2 by metallic mirror 1 boundary reflection, the optical cavity structure of design makes infrared light in thin silicide sensitive membrane 3 interface light intensity maximums, to increase the absorption of thin 3 pairs of reflecting part infrared lights of silicide sensitive membrane, the infrared photon of absorption excites the generation electron-hole pair.

Embodiment:

Referring to three layers of Schottky barrier infrared detector structural representation shown in the accompanying drawing 2, be the structure that preferred implementation of the present invention adopted, three layers of silicide sensitive film optical cavity structure Schottky barrier infrared detector shown in the figure; Be P type silicon layer at platinum family (platinum, iridium, palladium etc.) metallic film upper and lower surface, through platinum group metal film and P type silicon layer generation solid phase reaction, generate thin silicide sensitive membrane 3 (after being platinum group metal film and P type silicon layer generation solid phase reaction, be converted into thin silicide sensitive membrane 3), (above-mentioned P type substrate 5 and P type amorphous silicon 6 all belong to P type silicon to these silicide sensitive membrane 3 thickness with interior at 2nm, hereinafter dated especially as not having, referring to definition herein).

It is right that infrared light is absorbed excitation electron-holes by silicide sensitive membrane 3, and energy is greater than schottky barrier height and cross Schottky barrier less than the hole of critical escape angle be injected in the P type silicon layer in momentum space; Because thin silicide sensitive membrane 3 thickness are in 2nm, there is discontinuous micropore in the rete, hole under electric field action in the P type silicon layer enters P type substrate 5 and is pooled to the P+ electrode by the micropore in the thin silicide sensitive membrane 3, the electronics that stays in thin silicide sensitive membrane 3 floor is pooled to the N+ electrode by N type district, finishes photoelectric conversion process.

Have only one side that P type silicon layer is arranged in the structure of conventional optical cavity structure Schottky barrier infrared detector, satisfy after scattering repeatedly in the hole of silicide sensitive membrane 3/ silicon interface injection condition the hole (energy greater than schottky barrier height and in momentum space less than the hole of critical escape angle), owing to can not be injected in the P type substrate 5 at silicide sensitive membrane 3/ optical cavity medium 2 interfaces, the hole needs just can turn back to silicide sensitive membrane 3/ silicon interface through the distance of 2 times of silicide sensitive membrane 3 thickness, and incides in the silicon.

According to the theory of propositions such as Hammam Elabd, probability P is injected in the hole _tCan calculate by following formula:

$P_t=P\left(\mathrm{hv}\right)+P\left(\mathrm{hv}\right)\exp \left(\frac{-2t}{L}\right)+P\left(\mathrm{hv}\right)\exp \left(\frac{-4t}{L}\right)\·\·\·+P\left(\mathrm{hv}\right)\exp \left(\frac{-2\mathrm{nt}}{L}\right)$ ①

$n=\frac{L}{2t}\ln \left(\frac{\mathrm{hv}}{{\mathrm{\Ψ}}_{\mathrm{ms}}}\right)$ ②

In the formula: hv is photon energy (h is a planck constant, and v is the frequency of incident photon);

P (hv) is a hole escape probability;

T is silicide sensitive membrane 3 thickness;

L is the hole attenuation length;

N is that energy is the photon maximum scattering number of times of hv;

ψ _MsBe schottky barrier height;

Preferred embodiment of the present invention adopts the detector of three layers of silicide sensitive membrane 3 structure, because all there is P type silicon layer on silicide sensitive membrane 3 two sides, the hole of repeatedly satisfying injection condition after the scattering only needs can incide in the silicon through the distance of 1 times of silicide sensitive membrane 3 thickness, by to formula 1., 2. distortion, can obtain hole of the present invention and inject probability P _tComputing formula is as follows:

$P_t=P\left(\mathrm{hv}\right)+P\left(\mathrm{hv}\right)\exp \left(\frac{-t}{L}\right)+P\left(\mathrm{hv}\right)\exp \left(\frac{-2t}{L}\right)+P\left(\mathrm{hv}\right)\exp \left(\frac{-3t}{L}\right)...+P\left(\mathrm{hv}\right)\exp \left(\frac{-\mathrm{nt}}{L}\right)$ ③

$n=\frac{L}{t}\ln \left(\frac{\mathrm{hv}}{{\mathrm{\Ψ}}_{\mathrm{ms}}}\right)$ ④

In the formula: hv is photon energy (h is a planck constant, and v is the frequency of incident photon);

P (hv) is a hole escape probability;

T is silicide sensitive membrane 3 thickness;

L is the hole attenuation length;

N is that energy is the photon maximum scattering number of times of hv;

ψ _MsBe schottky barrier height;

4. formula is compared with 2. formula, and photon maximum scattering number of times increases by 1 times, for silicide sensitive membrane 3 thickness that are not more than 2nm, because L=250nm is more than 100 times of t, as L=250nm, t=2nm, ψ _Ms=0.21ev, v=10 ¹⁴When Hz, n=44, can get P _t3./P _t1.=1.976, inject the probability P of substrate _tIncreased about 1 times, promptly photoelectric conversion efficiency improves 1 times.

For thickness at 2nm with interior thin silicide sensitive membrane 3, IR transmittance is 45%, second and third layer (the thin silicide sensitive membrane 3 of the bottom be a ground floor, and the aftermentioned literal is referring to definition herein) approaches silicide sensitive membrane 3 and will effectively utilize the infrared light of transmission; With thin silicide sensitive membrane 3 photoelectric conversion efficiencys of ground floor is 1, and then thin silicide sensitive membrane 3 photoelectric conversion efficiencys of the second layer are that 0.45, the three layer of thin silicide sensitive membrane 3 photoelectric conversion efficiency are 0.20, add up to 1.65; Compare with conventional optical cavity structure Schottky barrier infrared detector structure, adopting the photoelectric conversion efficiency of three layers of silicide sensitive membrane 3 structure is 2 * 1.65, and the photoelectric conversion efficiency of multi-layer sensitive film optical cavity structure Schottky barrier Infrared Detectors promptly of the present invention is more than 3 times of conventional optical cavity structure Schottky barrier infrared detector.

Utilize image force to reduce the principle of schottky barrier height, the P type amorphous silicon 6 between the thin silicide sensitive membrane 3 can be made as conventional concentration (10 ¹⁴～10 ¹⁷Cm ^-3) P type doped layer, also can be made as high concentration (10 ¹⁸～10 ²¹Cm ^-3) P type doped layer; When P type amorphous silicon 6 thin layers satisfy the self-built gesture of Schottky barrier and can exhaust this thin layer fully, can reduce schottky barrier height, can not produce tunnel leakage current, make the Schottky barrier detector cut-off wavelength extend to LONG WAVE INFRARED zone (greater than 14 μ m), and improve near the photoelectric conversion efficiency of Schottky barrier detector cut-off wavelength; Employing is lower than 10 ¹⁷Cm ^-3P type amorphous silicon 6 thin layers of doping content, schottky barrier height can be with routine identical.

Referring to three layers of Schottky barrier infrared detector top view structural representation shown in the accompanying drawing 3, it shown in the figure multi-layer sensitive film optical cavity structure Schottky barrier Infrared Detectors top view structural representation, the difference of it and conventional optical cavity structure Schottky barrier infrared detector is: multi-layer sensitive film optical cavity structure Schottky barrier Infrared Detectors superposeed in silicide sensitive membrane district three floor P type amorphous silicons 6 and three floor silicide sensitive membrane 3, and this shows that multi-layer sensitive film optical cavity structure Schottky barrier Infrared Detectors manufacture craft of the present invention is similar and compatible to conventional optical cavity structure Schottky barrier infrared detector; Referring to accompanying drawing 3, two, three floor silicide sensitive membrane 3 of multi-layer sensitive film optical cavity structure Schottky barrier Infrared Detectors are connected as a single entity with ground floor silicide sensitive membrane 3 and silicon N type district by transition region (wherein transition region is the N type silicide that platinum group metal and 4 reactions of N type guard ring form).

Claims (7)

1. multi-layer sensitive film optical cavity structure Schottky barrier Infrared Detectors, it comprises: metallic mirror (1), optical cavity medium (2), silicide sensitive membrane (3), N type guard ring (4), N+ electrode, P+ electrode, P type substrate (5) and anti-reflective film (7) is characterized in that: described silicide sensitive membrane (3) can have multilayer; In twos between silicide sensitive membrane (3) and and optical cavity medium (2) between all accompany P type amorphous silicon (6); Each layer silicide sensitive membrane (3) all is connected with N type guard ring (4).

2. multi-layer sensitive film optical cavity structure Schottky barrier Infrared Detectors according to claim 1 is characterized in that: each layer silicide sensitive membrane (3) is wrapped up therebetween P type amorphous silicon (6) fully as a whole and is connected with N type guard ring (4); Optical cavity medium (2) will top layer P type amorphous silicon (6) and silicide sensitive membrane (3) outer surface cover fully.

3. multi-layer sensitive film optical cavity structure Schottky barrier Infrared Detectors according to claim 1, it is characterized in that: described silicide sensitive membrane (3) has three layers, then have three layers of P type amorphous silicon (6), wherein two-layer P type amorphous silicon (6) is clipped between three layers of silicide sensitive membrane (3), also has one deck P type amorphous silicon (6) to cover on the silicide sensitive membrane (3) of top layer.

4. multi-layer sensitive film optical cavity structure Schottky barrier Infrared Detectors according to claim 3 is characterized in that: the gross thickness of described three layers of silicide sensitive membrane (3) and three layers of P type amorphous silicon (6) is 5～25nm.

5. multi-layer sensitive film optical cavity structure Schottky barrier Infrared Detectors according to claim 4 is characterized in that: described silicide sensitive membrane (3) thickness is in 2nm.

6. multi-layer sensitive film optical cavity structure Schottky barrier Infrared Detectors according to claim 1 is characterized in that: described P type amorphous silicon (6), its doping content are 10 ¹⁴～10 ¹⁷Cm ^-3

7. multi-layer sensitive film optical cavity structure Schottky barrier Infrared Detectors according to claim 1 is characterized in that: described P type amorphous silicon (6), its doping content are 10 ¹⁸～10 ²¹Cm ^-3

Images