CN1993869A - Optical semiconductor device - Google Patents
Optical semiconductor device Download PDFInfo
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- CN1993869A CN1993869A CN 200580025643 CN200580025643A CN1993869A CN 1993869 A CN1993869 A CN 1993869A CN 200580025643 CN200580025643 CN 200580025643 CN 200580025643 A CN200580025643 A CN 200580025643A CN 1993869 A CN1993869 A CN 1993869A
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Abstract
The present invention provides an optical semiconductor device including a semiconductor thin film (4) having photoconductivity and a pair of electrodes (5) and (10) for applying an electric field to an inside of the semiconductor thin film (4) in a direction approximately vertical to a surface of the semiconductor thin film (4), wherein the semiconductor thin film (4) generates an electromagnetic wave when light is applied to a region thereof to which the electric field is applied. The electrodes are provided to a front surface and a back surface of the semiconductor thin film (4) with the semiconductor thin film interposed therebetween.
Description
Technical field
The present invention relates to as utilizing rayed to produce and surveying the mainly optical semiconductor device of the device of the frequency electromagnetic waves in the scope from the millimeter wave to the THz wave.
Background technology
In the last few years, developed the harmless detection technology that utilizes the electromagnetic wave (30GHz is to 30THz) in (THz) ripple scope from the millimeter wave to the Terahertz.The technology of developing in having the electromagnetic application of this frequency band comprises: the technology that use replaces the safe scintilloscope check system (safe radioscopic inspection system) of x-ray system to carry out imaging, be used to obtain the absorption spectrum of material inside or complex dielectric permittivity spectral technique with the couple state of assessment atom, be used for the technology of analysing biomolecules, and the technology that is used to assess carrier concentration or mobility.
JP10-104171A discloses the THz generating means of having used photocon suitably, wherein, provides the antenna that is used as electrode simultaneously on the photo-conductive film that is deposited on the substrate.It shown in Figure 10 detector 132 as the example structure of photocon.Substrate 30 has silicon on sapphire (silicon-on-sapphire) structure of for example crossing through radiation treatment, wherein, is deposited on the Sapphire Substrate as the silicon fiml of photoconductive material.Generally, the LT-GaAs of low-temperature epitaxy on the GaAs substrate is also through being often used as photoconductive film.The dipole antenna 138 that is formed on the surface comprises a pair of dipole antenna feed line (dipole feed line) 138a and 138b and a pair of dipole antenna arm 139a and 139b.133 places assemble in the gap in light pulse.When applying voltage, produce the THz pulse in both sides, described gap.When not applying the voltage detection photoelectric current, can detect the THz pulse.The electromagnetic template die (slab mode) (substrate pattern) that substrate lens 136 is used for being constrained on substrate 130 is coupled to the free space radiation mode, also is used for being controlled at the angle of radiation of electromagnetic wave spatial transmission pattern.
Illustrate by way of example above independent use photocon with electromagnetic wave propagation in the space.On the other hand, at volume the 1st phase (AppliedPhysics Letters on January 7th, 2002 " applicating physical communication " the 80th, vol.80, no.1) 154-156 page or leaf and on March 22nd, 2004 " applicating physical communication " the 84th roll up the 12nd phase (Applied Physics Letters, vol.84, no.12) a kind of little function element is disclosed in the 2049-2051 page or leaf, wherein, as the semiconductor film of photocon and the electromagnetic transmission path that is used to transmit generation be integrated into single substrate.This device has such structure: the film that only comprises the epitaxial loayer of the photocon that is formed by LT-GaAs is transferred on the part that is formed on the high-frequency transmission path on the substrate.According to " applicating physical communication " the 80th volume the 1st phase 154-156 page or leaf on January 7th, 2002, microstrip line (microstrip line) is formed on the Si substrate, accompanies the insulator resin therebetween.The gap is formed in the part of described line.The LT-GaAs film only is arranged in the bottom in described gap.On the other hand, according to " applicating physical communication " the 84th volume the 12nd phase 2049-2051 page or leaf on March 22nd, 2004, coplanar striplines (coplanar strip line) is formed on the quartz substrate.Be arranged as to the LT-GaAs film portion gap of passing between described two lines.
Each device is carried out and is driven, and so just can pass through spatial transmission, laser beam is applied to the metal wire gap from the face side of substrate passes through described line propagation with the THz electromagnetic wave that allows generation.
Summary of the invention
In above-mentioned integrated device, be difficult to improve coupling efficiency and be difficult to keep stability, its reason is that laser beam is to aim at by space coupling and photocon.Because the described gap portion of photocon is formed on substrate surface, can not laterally apply light (laterally).So just can not realize exempting from aiming at by fiber waveguide is provided on substrate.In other words, also exist such as sensing sensitivity, overall measurement time and manufacturing cost etc. problem to be solved is arranged.
In addition, because electric field is applied in by surface electrode, the internal electric field of LT-GaAs is inhomogeneous and can not control the behavior of the charge carrier that is excited by laser beam effectively.In addition, aspect clearance gap, need accurate photoetching to come high reproducibility ground to form 1 micron or littler narrow gap, be used to control electric field strength, therefore cause the increase of manufacturing cost.All there is similar problem in permission by electromagnetic single photocon of spatial transmission and integrated device.
The invention provides photocon and comprise photocon and the integrated device of THz transmission path etc., wherein, be positioned at gaps between electrodes at interval and the electric field on the described gap can easily control with a simple structure.The present invention also provides a kind of structure, is used to improve and the coupling efficiency when being stabilized in and will being applied to the optical coupling of gap portion.
The invention provides and comprise the semiconductive thin film with photoconduction and the optical semiconductor device of pair of electrodes, wherein this is used for applying electric field in the direction of the front surface that is approximately perpendicular to described semiconductive thin film to this semiconductive thin film inside to electrode, wherein, described semiconductive thin film receives light to generate electromagnetic waves in an one zone, this zone is the zone that has been applied in electric field.
In addition, the invention provides a kind of sensing device, it comprises electromagnetic wave generating device and is used to survey electromagnetic electromagnetic wave detection device, described electromagnetic wave generating device has the semiconductive thin film and the pair of electrodes of band photoconduction, this is used for applying electric field in the direction that is substantially perpendicular to described semiconductive thin film surface to the inside of this semiconductive thin film to electrode, described semiconductive thin film has been applied at it and has received light in zone of electric field to generate electromagnetic waves, wherein, the change of the electromagnetic wave propagation state that sensing is caused by the object in the electromagnetic wave transmission path is with the information of the state that obtains relevant this object.
According to optical semiconductor device of the present invention, a kind of photocon can be provided, wherein the electric field on gaps between electrodes spacing and the described gap can be controlled with simple structure.In addition, can provide a kind of structure, this structure improves and has stablized the coupling efficiency with the optical coupling that will be applied to gap portion the time.In view of above aspect, a kind of Terahertz sensing device can be provided, it can be worked under low-voltage, and size is little, has the sensing optical system of easy adjusting, and has high stability and signal to noise ratio.Utilize this sensing device, possibility is low-cost and carry out the analysis of biomaterial, organic substance or semi-conducting material in high sensitivity, the Noninvasive of human body or noncontact sensing, the sensing that object's position changes etc.
Other features and advantages of the present invention will be more readily apparent from by the description below in conjunction with accompanying drawing, and wherein in institute of the present invention drawings attached, similar Reference numeral is indicated same or analogous parts.
Description of drawings
The accompanying drawing that comprises in this manual and constitute the part of this specification illustrates embodiments of the present invention and is used from specification one explains principle of the present invention.
Fig. 1 is the structure chart of the integrated device of first embodiment of the invention, and Figure 1A is along the cross-sectional view of 1A-1A among Fig. 1;
Fig. 2 A, 2B, 2C, 2D, 2E and 2F illustrate the method for making integrated device, and Fig. 2 BT, 2DT, 2ET and 2FT are respectively the top view of Fig. 2 B, 2D, 2E and 2F;
Fig. 3 illustrates the driving optical system according to integrated device of the present invention;
Fig. 4 illustrate second embodiment of the invention integrated device and the configuration of drive system;
Fig. 5 is the structure chart according to the integrated device of the 3rd execution mode of the present invention, and Fig. 5 B and 5C are respectively along the cross-sectional view of 5B-5B and 5C-5C among Fig. 5;
Fig. 6 is the cross-sectional view according to the photocon part of the 4th execution mode of the present invention;
Fig. 7 is the cross-sectional view according to the photocon part of the 5th execution mode of the present invention;
Fig. 8 is the plane graph according to the integrated device of the 6th execution mode of the present invention;
Fig. 9 illustrates the optical system according to the 6th execution mode of the present invention;
Figure 10 illustrates traditional photocon.
Embodiment
The present invention is characterised in that: apply electric field in the direction that is approximately perpendicular to described semiconductive thin film surface to the inside of this semiconductive thin film.Particularly preferably be front surface and rear surface that electrode or collimator electrode (quasi-electrodes) are formed on semiconductive thin film, semiconductive thin film is clipped in therebetween as photoconductive film, can apply voltage in the direction of film thickness like this.Manufacture method in the example that is used for realizing this structure preferably forms electrode on the photoconductive film that is formed on first substrate, stay photoconductive film then when being attached to second substrate, removes described first substrate.Electrode or be formed from the teeth outwards as the electromagnetic transmission line of electrode simultaneously then, thus obtain being formed on photocon on described second substrate.
The electromagnetic wave that produces at photocon can former state be transferred to the electromagnetic wave transmission path that is used as electrode simultaneously.Can provide antenna to transmission path to space radiation.Perhaps, the photocon with spline structure can be used as the THz detector.Can be guided to described THz detector effectively by the electromagnetic wave that antenna and transmission path are propagated.Electromagnetic wave detection part and part takes place to interconnect each other and be integrated on the same substrate by electromagnetic wave transmission path.
In addition, fiber waveguide can be integrated into from the side surface coupling light of the photocon that can vertically be applied voltage.The light beam that is used for photoexcitation can pass through Optical Fiber Transmission, and wherein optical fiber can be fixed to the fiber waveguide of aligning.The high stability THz generator/detector that need not to regulate optical system so just is provided.
The semiconductive thin film that can vertically be applied voltage can be single composition, maybe sandwich construction can be arranged.Particularly, the III-V family semiconductive thin film that preferably forms by the III-V compounds of group.Under the situation of single composition, for example, the LT-GaAs of molecular beam epitaxial method in low temperature (200 ℃ to 300 ℃) growth adopted in being to use of being fit to.Distance between electrodes can be controlled by the thickness of epitaxially grown film, can have high reproducibility ground like this and electric field strength is set accurately.Under the situation of sandwich construction, form heterojunction structure sandwiching the light absorbing zone that thickness reduces to about 100 nanometers and fully mixed between the semiconductor layer of broad-band gap having, thereby realize the high mobility and the short life of charge carrier simultaneously.The invention is not restricted to this, can stacked different conduction-types maybe can with semiconductor.As mentioned above, control the gap that is applied in electric field with nanoscale,, can solve the surface-treated problem like this at aspects such as reproducibility, costs by the thickness of control epitaxial film is next.
The following describes photocon and the execution mode that comprises the integrated device of photocon as the optical semiconductor device that produces and survey Terahertz.Material, structure, device etc. all are not limited to explanation provided here.In addition, except the explanation that provides, can utilize the various uses of element and the electromagnetic various characteristics that is produced here.
First execution mode
First embodiment of the invention, the photocon, fiber waveguide, the microstrip line that are used for light is converted to terahertz electromagnetic wave are integrated into same substrate, as shown in Figure 1.
Ti/Au electrode (or Al electrode) 7 is formed in the subregion on the Si substrate 1 as ground plane (ground plane).The low temperature that thickness is 2 microns (LT) growth GaAs epitaxial film 4 is transferred near the center.Fiber waveguide 3 is formed on the left side of LT-GaAs, and the light beam that enters from the outside carries out rayed to the side surface of LT-GaAs film effectively like this.On the other hand, Ti/Au microstrip line 5 is formed on the right side at top, and accompanies insulator 2, and the electromagnetic wave that produces at LT-GaAs can be propagated like this.This line is used as the top electrode of LT-GaAs simultaneously.Patch antenna (patch antenna) 6 is formed on another end portion of this line, and electromagnetic wave 9 can be by space radiation like this.This antenna is a wide-band type, is shaped as the convergent shape with transmitting pulse waveform effectively.
Referring to the cross-sectional view (Figure 1A) along the 1A-1A among Fig. 1, insulator 2 only has openning 11 to obtain electrode contacts at the top of LT-GaAs.Insulator 2 right end partly have cut-out 12, to obtain to be used to apply the terminal on the voltage 8 to LT-GaAs.The AuGe/Ni/Au electrode 10 that is used for contacting with LT-GaAs is used the Au fusion of the end face of AuSn scolder (not shown) and ground plane 7.
Above-mentioned configuration allows photocon to apply in the direction perpendicular to the film thickness of LT-GaAs under the situation of uniform electric field to work, as shown in Figure 1.In addition, gap clearance can be limited by the thickness of epitaxial film, has therefore realized high precision and reproducibility.Generally, the size of substrate is little of about 1 square centimeter generally.Though fiber waveguide has the cross section of about 10 square microns, can bring up to 50 square microns to improve coupling efficiency in light beam entering part size.On the contrary, be used near the point of LT-GaAs irradiation, thickness direction can reduce to 2 microns, and convergent is to adjust size (not shown).Micro belt line width is 15 microns.When driving the LT-GaAs that is transferred as photocon, the width of top electrode is defined as 10 microns by insulator window 11.Benzocyclobutene (Benzocyclobutene (BCB)), polysilane (polysilane) or polyimides (polyimide) are suitable as insulator, and it is easy to processed and has low dielectric absorption when high frequency.Thickness is set to about 6 microns.Above-mentioned size or material only are used for the invention is not restricted to this for example.
Though use patch antenna (patch antenna) as antenna as an example, also can use dipole antenna, helical antenna, F-antenna etc.In addition, by transmission line being converted to slot line or complanar line, can use bowknot (bow-tie) antenna or the slot aerial of surface type.Perhaps, can integrated Yagi antenna, horn antenna waits the controlling party tropism.
Referring now to Fig. 2 A, 2B, 2C, 2D, 2E and 2F,, use description to make the method for the described device of this execution mode below.To identify with same numeral with components identical among Fig. 1.It should be noted that Fig. 2 BT, 2DT, 2ET and 2FT are respectively the top view of Fig. 2 B, 2D, 2E and 2F.
In Fig. 2 A, as the AlAs layer 21 of 100 nanometer thickness of the sacrifice layer that is used to remove substrate and at the LT-GaAs layer 22 of 2 micron thickness of 250 ℃ low-temperature epitaxy by growths on GaAs substrate 20 such as molecular beam epitaxy (MBE) methods.
In Fig. 2 B, on the LT-GaAs surface, form AuGe/Ni/Au electrode 10 and form alloy at 40 ℃.Carry out 20 to 120 microns of mechanical polishinges on the GaAs substrate, the result obtains the chip 23 of about 200 square microns.In addition, in order to increase the thickness of described chip, electrode 10 can be by gold-plated to have 3 microns thickness.In the subregion that is pre-formed the ground plane 7 on Si substrate 1, form the AuSn scolder.Handle chip 23 to be placed on desirable position, pass through heating and fusing then.When carrying out in chip side when gold-plated, subsequently can be by electroplating or deposit provide Sn from the teeth outwards.Can use static tweezers (electrostatic tweezer) etc. to handle chip one by one.Perhaps, at wafer scale, a plurality of chips can be combined on glass substrate etc. with desired spacing temporarily, are fused together then.
In Fig. 2 C, the GaAs substrate of the chip that has fused will be removed.In this case, when being coated with organic material etc. around the chip 23, the mixed solution that uses hydrogen peroxide and ammoniacal liquor is with 10 microns/minute speed etching GaAs.The described AlAs of being etched in layer stops.Use concentrated hydrochloric acid to remove the described AlAs that is used as sacrifice layer.
In Fig. 2 D, carry out photoetching and wet etching in mode similar to the above, be reduced to 100 microns * 50 microns with the size of the LT-GaAs that will be transferred.This etching purpose also is to remove the damaged layer of LT-GaAs sidewall.Here, the part 25 that stays behind etching GaAs of electrode 10 can be removed by carrying out metal etch.
In Fig. 2 E, be used for the fiber waveguide 3 and the insulator 2 of microstrip line by coating BCB and photoetching manufacturing.By at first using photosensitive BCB to form core layer, apply non-photosensitivity BCB then on the whole, embed described fiber waveguide 3.The photosensitive BCB that the described non-photosensitivity BCB of refractive index ratio is higher is used as fiber waveguide.After whole surface is by non-photosensitivity BCB planarization, by photoetch and by using oxygen and CF
4The reactive ion etching (RIE) of mist be formed for the window 11 of the electrode of LT-GaAs.
In Fig. 2 F, form by peeling off (lift-off) method as the Ti/Au electrode of the top electrode of LT-GaAs and microstrip line and antenna.
In the description in front, used BCB as an example.Also can use polyimides to be used for making similarly.Perhaps, in the method for using photosensitive polysilane, can make fiber waveguide by changing refractive index with the exposure control degree of polymerization.
Fig. 3 illustrates the drive system that integrated vertical electric field according to the present invention applies the type photocon.When using the THz pulse as the generation electromagnetic field, ultrashort pulse by titanium sapphire femto-second laser (titanium sapphire femto second laser) 30 produces about 100 femtoseconds (fsec) is divided into pump beam (pump beam) and probe beam (probe beam) with half-reflecting mirror 36 afterwards.Described pump beam is coupled to the light beam upstream end according to integrated device 31 of the present invention, to produce THz electromagnetic wave 35.The packaged lens (Hemispherical lens) 32 that is used to improve beam direction is combined in the top of the antenna of launching electromagnetic wave.Described THz electromagnetic impulse is received through wanting checked object 33 and the antenna place on the detection side (towards the back) of integrated device 34.Integrated device 34 can have the structure the same with side device 31 takes place.For purposes as detector, the electric current that between the electrode of surveying under the situation that does not apply electric field at photocon, flows.Enter the timing that postpones optical system 38 by adjusting probe beam, can obtain the electromagnetic impulse waveform and need not high speed electronics.By waveform analysis come measuring amplitude to change, propagation delay, fourier spectrum change etc. can be checked the physical attribute of sample 33 etc. relatively.Usually, intensity of laser beam on average is approximately several mW, repeats with about 80MHz, and the voltage that is applied to photocon is approximately 10 volts.Under the situation that vertical voltage applies, described gap clearance is 2 microns according to the present invention, and it is less than 5 microns of normally used surface electrical polar form.Therefore, being used to obtain the voltage that same electric field intensity applies can be lowered.
Can comprise various objects such as organic material, semi-conducting material, living materials with harmless and non-contacting mode inspection.By two-dimensional scan, can also obtain distributed image to object.
Be inserted into detection blood vessel pattern or fingerprint in the electromagnetic wave propagation path by finger tip, also can carry out the identification and the personal verification of skin condition, blood flow (for example, blood pulse), blood component etc. the people.
In addition, the present invention also can be effective to the actinoscopy of the inside of thickness, number or the paper of embedded object or plastics.
Above-described this execution mode provides semiconductor device, and wherein the vertical electric field that is made of LT-GaAs applies the type photocon and microstrip line, antenna and fiber waveguide integrate.But certainly, photocon also can be used as the work of electromagnetic wave generating device individually.In this case, light beam can be applied in from the side or can be applied near extremely from power on top.In order to increase radiation efficiency, the shape of top electrode can image antenna.
Though at this GaAs family has been described, can have used other semiconductor such as InP or InAs.Perhaps, can use organic semiconductor with photoconduction.
Second execution mode
Second embodiment of the invention, a plurality of elements are arranged on the same Semiconductor substrate, shown in the integrated device among Fig. 4 40.In the manufacturing process in the first embodiment, element is formed on the Si substrate 41 with wafer scale together, like this, according to the layout of described element or the mode of cut crystal, can freely provide the element of arrangement.
More specifically, be arranged in parallel two fiber waveguide 42a and 42b, photocon 47a and 47b, microstrip line 43a and 43b and print dipole antennas 44a and 44b.Though arrangement pitches is illustrated as 1 centimetre here, the invention is not restricted to this.Under this situation, the THz electromagnetic wave comprises the component by spatial transmission as shown in arrow 46, can detect the electromagnetic variable condition of reflection on object 45 like this.
With regard to optical system, although can use femto-second laser shown in first execution mode, here in order to reduce cost and size is used two semiconductor lasers 48.When the oscillation wavelength of the single-mode oscillation of two semiconductor lasers was slightly different, the laser beam that coupler 49 will be applied to the input of fiber waveguide 42a mixed, and photocon 47a can produce the electromagnetic wave corresponding to difference frequency (beat, beat) component like this.By change the amount of difference frequency when stablizing, the electromagnetic frequency of oscillation of the THz of CW can change in the scope of 3THz at about 0.1THz.At receiver side, when inciding fiber waveguide 42b by time adjusting device 50, photocon 47b uses its light mixed function to go to survey the electromagnetic intensity that receives by antenna 44b.Described time adjusting device 50 is carried out the phase place adjustment that light mixes.The detection of carrying out when changing beat frequency (beatfrequency) can measure the reflectance spectrum of object, to discern physical attribute in first execution mode.
Use reflection measurement, can survey the physical characteristic of the relatively large material of absorptivity, its film thickness, its rough surface state etc.About using human body, can check material in skin surface state for example coarse or ageing state, pore state, water content, collagen, Fat Distribution, blood flow or the blood etc.
Perhaps, by measuring the electromagnetic time of delay of reflection the position change of all right sensed object 45.Under this situation, with the triangular wave semiconductor laser modulation of dozens of megahertz (MHz), to use the THz electromagnetic wave to carry out location recognition according to known FMCW method, this can obtain the position telemetry device of high-resolution (＜100 microns).
Fig. 4 symbol illustrates an optical system.When laser beam sources did not provide ultrashort pulse, still, optical fiber was used to propagate, and it is more having superiority aspect efficient and the space.Can realize by following manner with the coupling of integrated device: directly be connected coupling, insert lens, or provide and anchor leg (pigtail) at optical fiber connector, therefore, reduced the overall size of the device that comprises light source with the alignment so that has improved coupling efficiency.Also can be and the fibre system combination, can be with on the plane optical circuit of semiconductor laser installing to the Si substrate, and and the integrated device that is integrated with photocon integrate.
The 3rd execution mode
According to the 3rd execution mode of the present invention, as shown in Figure 5, two photocons are integrated on the same substrate.This allows sensing device to work on substrate, is used for the object that sensing is placed near high frequency transmission line.
Similar in the photocon 53a and first execution mode: online 54 and bottom electrode 52a between apply vertical electric field, propagate by line 54 by the light activated THz electromagnetic wave of propagating by fiber waveguide 51a.In this embodiment, do not provide ground plane, high frequency transmission line is the single line that comprises the holding wire 54 that embeds up and down in the insulator 55.Electrode 52a and 52b isolate, and each has about 3 microns thickness, and are coated with gold to be used to adjust the height of photocon.
Therefore, manufacturing process is almost identical with first execution mode, and difference is, is patterned and increases thickness at the electrode 52a of Si substrate 1 side and 52b, and forming the transmission line 54 that also is used as electrode, this transmission line is covered about 3 microns at the top by same insulator then.Referring to understanding this point easily along the cross-sectional view (Fig. 5 B) of 5B-5B with along the cross-sectional view (Fig. 5 C) of 5C-5C.As along shown in the cross-sectional view of 5B-5B,, provide through hole electrode 57a to be used to obtain electrode contacts because insulator 55 online 54 is embedded into after forming.In addition,, hole 56 is provided for the mid portion of transmission line, is used to increase the electromagnetic penetrability of propagation as along shown in the cross-sectional view of 5C-5C.Will be placed in this hole to be checked efficiently by checked material.
Similar in the external optical system and first execution mode: the pump beam that produces from the titanium sapphire femto-second laser is introduced to THz electromagnetic wave generation side waveguide 51a, is introduced to detection side waveguide 51b and survey bundle by postponing optical system.
In this system, survey the change of spread state on transmission line 54 at photocon 53b place, can discern the object on the transmission path like this.At the photocon 53b place of detection side, the photoelectric current of generation can apply electric field and be measured, as in first execution mode.
Electromagnetic wave penetrates in the hole 56 that comprises sample as evanescent wave (evanescent wave), and spread state changes according to the attribute of the object that is comprised.Particularly, the absorption or the propagation delay of attenuation of Electromagnetic, specific frequency components can take place in signal variation.This causes comparing size with the traditional measurement of usage space optical system and significantly reduces, reduced element quantity, improved stability and coupling efficiency and improved signal to noise ratio.
In addition, the liquid that can't measure traditionally, powder etc. just are placed in the hole 56 measured.For example, biogenic material should be measured in order to analyze in solution as amino acid, DNA (deoxyribonucleic acid) (DNA) or protein than material.The invention provides biological sensor, its high-frequency dielectric performance of utilizing under solution state is to be difficult to the assessment carried out traditionally.
Although should be noted that as optical system femto-second laser has been described, can use semiconductor laser and optical fiber to reduce the integral device size, shown in second execution mode.
The 4th execution mode
According to the 4th execution mode of the present invention, a kind of structure is provided, it allows to increase field intensity and allows the electronics high-speed motion.
Fig. 6 is the photocon cross-sectional view partly of the integrated device of similar first execution mode.Described structure except photocon with first execution mode in identical, in the described photocon, the epitaxial film that is transferred has multi-layer film structure.Shown the n type Al0.08 Ga0.92As that is designated " 65 " among the figure in normal growth temperature (about 600 ℃) growth, be designated the n type Al0.2 Ga0.8As of " 66 ", be designated the not Doped GaAs of " 67 ", the n type Al0.2 Ga0.8As that is designated the n type Al0.08 Ga0.92As of " 68 " and is designated " 69 ".Described n type layer is by high doped.Particularly, " 65 " and " 69 " make electrode contacts have low the absorption to the exciting light of 800 nanometers.In order to obtain about 2 microns gross thickness, the thickness that makes " 66 " and " 68 " is 1 micron and other thickness is 100 nanometers.The absorption of exciting light occurs at the unadulterated GaAs absorbed layer 67 with 100 nano thickness, like this, the charge carrier of generation can rapid movement and is bumped with lattice hardly.This execution mode adopts normal temperature growth, and comparing with LT-GaAs provides good degree of crystallinity.Therefore, mobility of charge carrier rate height and the life-span of charge carrier can shorten is because the charge carrier that produces is from the very fast arrival of absorbed layer N type layer.In addition, very thin as the described absorbed layer of electric field applied layer, therefore make and can under low-voltage, work.In addition, do not have to use the carrier capture of the defect layer that the gathering (As cluster) by arsenic causes, the result is that heat production minimizing and film quality improve.Because the variation that often has under the situation of using LT-GaAs has tailed off, element characteristic is stable, and the output height.Traditionally, showed outstanding feature, because thin absorbed layer and can not improve launching efficiency though be used to produce the photocon of THz.The execution mode of this horizontal incident type provides longer absorption, thereby has fully improved efficient.
Though should be noted that and for example understand the n-i-n structure here, can adopt m-i-n (metal-intrinsic-n type) structure or the p-i-n structure of use schottky junction, to apply opposite electric field.The explanation that the composition of described layer and thickness are not limited to here to be done.
The 5th execution mode
According to the 5th execution mode of the present invention, provide vertical electric field to apply the type photocon, and do not had the transfer process in first execution mode.
Fig. 7 illustrates its cross-sectional view.Use Semi-insulating GaAs 70 as substrate.Adopt the epitaxial growth of MBE method to be used to make the n type Al0.08 Ga0.92As layer 71 and the LT-GaAs layer 72 of electrode contacts.Insulating barrier 73 is similar with the counter element in first execution mode with top electrode 74.
For bottom electrode, to obtain the effect of metalloid, the electrode of imbedding 75 is realized contact to n type layer 71 by high doped.Electrode 75 is configured to make by constituting alloy electrode in the part that contacts with n type AlGaAs by AuGe/Ni/Au, and by its thickness of gold-plated increase.Contact layer is made of to reduce the absorption to the light that is used to excite AlGaAs.
Can use the photocon of above-mentioned configuration separately.Perhaps, its can be configured to first to the 3rd execution mode in the same integrated device.In this method of not using transfer, can greatly simplify manufacture process.
The 6th execution mode
Fig. 8 is the plane graph according to the integrated device of photocon, electromagnetic wave transmission path and the antenna of the 6th execution mode of comprising according to present embodiment.
The surface-coated of substrate 81 has Au film and the BCB as grounding electrode, and its general thickness is 3 microns.Subregion 80 does not have BCB, to make grounding electrode.1 square millimeter LT-GaAs film 89 is transferred as in first execution mode.The BCB window that 500 square microns are provided to described subregion 90 is to expose the surface of LT-GaAs film.Top electrode 88 is provided, makes to be that 20 microns Ti-Au line 87 applies on the surface that is biased into LT-GaAs from described window zone 90 by width.Making width is that 5 microns microstrip lines 84 that are used to transmit by shine the terahertz electromagnetic wave of LT-GaAs generation with short pulse laser beam have the characteristic impedance that is adjusted to about 70 Ω.The terahertz electromagnetic wave that provides the patch antenna 82 of about 90 square microns to be used for propagating by microstrip line is radiated the space.Form otch 83, to carry out impedance matching, the feasible about 30 microns degree of depth of end surface that reaches relative antenna from the load point (feed point) of transmission path.
Apply laser beam near spot about 5 microns the top electrode of LT-GaAs, shown in position in the enlarged drawing 86.Low pass filter 85 is provided for the part of top electrode, is used to prevent that frequency electromagnetic waves from propagating into electrode pad 88, shown in Fig. 8 enlarged drawing.Near the part position 86 that being used to of Ti/Au line 87 carried out laser beam irradiation can have otch or protuberance, to improve luminous efficiency.
Driving utilizes the mode of the sensing of terahertz electromagnetic wave can be the same with above-mentioned execution mode.Fig. 9 illustrates the optical system of the example of using this device.According to the photocon part 91 of the integrated device 90 of this execution mode by by light beam 97 irradiations of speculum 95 and lens 96 from femto-second laser.The terahertz electromagnetic wave that produces from integrated device 90 passes through spatial transmission by two parabolic mirrors (parabolic mirror) 92 and 93, shown in 98, is received by detector 94 then.Here, the femto-second laser light beam can be branched and propagate into detector 94 by delay system (not shown), is used for well-known coherent detection (time-domain spectroscopy detection (timeregion spectrum detection) etc.).
Here, carry out the transmission line of Terahertz waveform and the impedance matching between the antenna, make the electromagnetism wave energy effectively radiation enter the space, the sensitivity when therefore having improved the object on the sensing transmission line, the same in first execution mode that coexists etc.
Can not carry out many significantly different execution modes owing to do not break away from the spirit and scope of the invention, therefore be understood that the qualification that the invention is not restricted to concrete execution mode and only be subjected to claims.
The application requires the priority of Japanese patent application No.2004-22365 6 that proposed on July 30th, 2004 and the Japanese patent application No.2005-025210 that proposed on February 1st, 2005, and these two parts of applications are incorporated among the application by reference.
Claims (10)
1. optical semiconductor device, it comprises:
Semiconductive thin film with photoconduction; And
Be used for applying the electrode pair of electric field to the inside of this semiconductive thin film in the direction of the front surface that is approximately perpendicular to described semiconductive thin film,
Wherein said semiconductive thin film is applied at it and receives light in zone of electric field to generate electromagnetic waves.
2. optical semiconductor device as claimed in claim 1, wherein said electrode pair are disposed on the front surface and the back side of described semiconductive thin film, and the described semiconductive thin film of sandwich toward each other.
3. optical semiconductor device as claimed in claim 1, wherein said semiconductive thin film is made of the III-V compounds of group.
4. optical semiconductor device as claimed in claim 1 wherein is coated with the semiconductor of different conduction-types at least one surface of described semiconductive thin film.
5. optical semiconductor device as claimed in claim 1 comprises also being used to propagate the electromagnetic transmission path that produces from described semiconductive thin film that wherein said transmission path is electrically connected to one of described electrode.
6. optical semiconductor device as claimed in claim 1 also comprises being used for the electromagenetic wave radiation that will produce from the described semiconductive thin film antenna to the space.
7. optical semiconductor device as claimed in claim 1 also comprises:
Transmission path is used to propagate the electromagnetic wave that produces from described semiconductive thin film; And
Antenna, the electromagenetic wave radiation that is used for producing from described semiconductive thin film be to the space,
Wherein said transmission path and described antenna mutually coupling so that the impedance of the impedance of described transmission path and described antenna each other about equally.
8. optical semiconductor device as claimed in claim 1 further comprises fiber waveguide, and it is used for light is applied to from the side of described semiconductive thin film the described zone that is applied in electric field of described semiconductive thin film.
9. optical semiconductor device as claimed in claim 1, wherein said electromagnetic frequency range at 30GHz between the 30THz.
10. sensing device, it comprises:
Electromagnetic wave generating device is used to generate electromagnetic waves;
Described electromagnetic wave generating device has: semiconductive thin film and the electrode pair that is used for applying to the inside of this semiconductive thin film in the direction on the surface that is approximately perpendicular to described semiconductive thin film electric field that photoconduction is arranged;
Described semiconductive thin film is applied at it and receives light in zone of electric field to generate electromagnetic waves; And
The electromagnetic wave detection device is used to survey electromagnetic wave,
Wherein, the change of the electromagnetic wave propagation state that causes by the object in the electromagnetic wave transmission path of sensing.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP223656/2004 | 2004-07-30 | ||
| JP2004223656 | 2004-07-30 | ||
| JP025210/2005 | 2005-02-01 |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2010101352550A Division CN101794835B (en) | 2004-07-30 | 2005-07-28 | Optical semiconductor device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1993869A true CN1993869A (en) | 2007-07-04 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200580025643 Pending CN1993869A (en) | 2004-07-30 | 2005-07-28 | Optical semiconductor device |
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| Country | Link |
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| CN (1) | CN1993869A (en) |
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