Summary of the invention
The object of the present invention is to provide a kind of GaN base biology sensor and preparation method thereof; when adopting silicon nitride, monox inorganic material to encapsulate in solution prior art; material easily occurs that in test process liquid ions infiltrates the problem that protective seam causes device failure; and when adopting photoresist to encapsulate, the unsuitable technical matters of prolonged application in organic environment of device.
For achieving the above object, the invention provides following technical scheme:
The embodiment of the present application discloses a kind of GaN base biology sensor, comprising:
Substrate;
Be formed at the AlGaN/GaN heterojunction on described substrate;
Be positioned at the source electrode on described AlGaN/GaN heterojunction and drain electrode, described source electrode and drain electrode are of a size of 0.25 mm
2~ 25mm
2, the distance between described source electrode and drain electrode is 0.5mm ~ 5mm;
Be packaged in the layer of silicone in described source electrode and drain electrode outside.
Preferably, in above-mentioned GaN base biology sensor, the material of described substrate is selected from sapphire or silicon.
Preferably, in above-mentioned GaN base biology sensor, described AlGaN/GaN heterojunction comprises the first GaN layer be formed at successively on described substrate, AlGaN layer and the second GaN layer.
Correspondingly, the embodiment of the present application also discloses a kind of method for making of GaN base biology sensor, comprising:
S1, at Grown AlGaN/GaN heterojunction;
S2, utilize electron beam evaporation process on AlGaN/GaN heterojunction evaporation Ti/Al/Ni/Au as drain electrode, evaporation Ni/Au as source electrode, described source electrode and drain electrode are of a size of 0.25 mm
2~ 25mm
2, the distance between described source electrode and drain electrode is 0.5mm ~ 5mm;
S3, employing silicone carry out packaging protection to source electrode and drain electrode.
Preferably, in the method for making of above-mentioned GaN base biology sensor, described AlGaN/GaN heterojunction comprises the first GaN layer be formed at successively on described substrate, AlGaN layer and the second GaN layer.
Preferably, in the method for making of above-mentioned GaN base biology sensor, the material of described substrate is selected from sapphire or silicon.
Compared with prior art; the invention has the advantages that: GaN base biology sensor of the present invention is of a size of a millimeter magnitude; silicone is adopted to encapsulate source electrode and drain electrode; solve material in test process, easily occur that liquid ions infiltrates the problem that protective seam causes device failure, and the unsuitable technical matters of prolonged application in organic environment of device.Meanwhile, GaN base biology sensor size becomes large and adopts the packaged type of silicone, does not affect the performance of sensor.In addition, the encapsulation of silicone can adopt the plant equipment of manual type or low cost, avoids the problem that the packaging cost of photoresist, silicon nitride and monox three kinds of packaged types is high.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, be described in detail the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, the every other embodiment that those of ordinary skill in the art obtain under the prerequisite not making creative work, all belongs to the scope of protection of the invention.
Shown in ginseng Fig. 1, GaN base biology sensor comprises substrate 1, and is formed at the first GaN layer 2 on substrate 1, AlGaN layer 3 and the second GaN layer 4, first GaN layer 2, AlGaN layer 3 and the second GaN layer 4 successively and forms AlGaN/GaN heterojunction.
The material of substrate 1 is selected from sapphire or silicon, is preferably sapphire.
AlGaN/GaN heterojunction is formed with source electrode 5 and drain electrode 6, source electrode 5 and drain electrode 6 are preferably dimensioned to be 0.25 mm
2~ 25mm
2, the distance between source electrode 5 and drain electrode 6 is preferably 0.5mm ~ 5mm.The material of source electrode 5 and drain electrode 6 has Ti, the combination of the metals such as Ta, Zr, Co, Al, Pt, Pa, Ni, Cr, Mo, W, Au, is preferably Ti/Al/Ni/Au combination.
Source electrode 5 and drain electrode 6 are electrically connected with contact conductor 7 respectively, and contact conductor 7 is drawn in the side of device.The material of contact conductor 7 has Ti, the metals such as Ta, Zr, Co, Al, Pt, Pa, Ni, Cr, Mo, W, Au, Cu, Fe and combination thereof, is preferably Ni/Au.
Source electrode 5 and drain electrode 6 and contact conductor 7 are packaged with layer of silicone 8, when layer of silicone 8 can prevent from carrying out liquid detecting, liquid and source electrode 5, drain 6 and go between 7 contact.The more important thing is, adopt silicone encapsulate, liquid ions not easily infiltrates protective seam, and device can prolonged application in organic environment.
Source electrode 5 and drain electrode 6 convexedly stretch in the surface of the second GaN layer 4, surround a sensing chamber 9 between source electrode 5 and drain electrode 6, can drip liquid to be detected in sensing chamber 9.The surface of the second GaN layer 4 defines in sensing chamber 9 sensing unit, sensing unit is directly modified with molecule film (not shown), the direct modification at this place refers to that molecule film is directly modified in the second GaN layer 4, does not need by Au film or oxide passivation layer film fixing biological molecules film.
Molecule film can be used for sessile antibody, DNA, preferably adopts to form biological reagent that tail base is-COOH on GaN surface or tail base is the biological reagent of-N2H, such as 3-aminopropyl triethoxysilane.
The method for making of above-mentioned GaN base biology sensor comprises:
S1, first employing metal-organic vapor phase epitaxy method (MOCVD) grow the first GaN layer 2, AlGaN layer 3 and the second GaN layer 4 on a sapphire substrate successively;
S2, photolithographic exposure go out ohmic contact regions, utilize electron beam evaporation, and at ohmic contact regions evaporation Ti/Al/Ni/Au, anneal 45 seconds under N2 environment after stripping, annealing temperature is 880 DEG C, form source electrode 5 and drain electrode 6.The size of source electrode 5 and drain electrode 6 is 2mm × 2mm, and source electrode 5 is 2mm with the spacing of drain electrode 6;
S3, photoetching, expose contact conductor 7 region, utilizes electron beam evaporation technique evaporation Ni/Au, and the rear lift-off of utilization technique separates outside lead;
S4, employing silicone carry out the encapsulation of device, protection source-drain electrode;
S5, device are modified, before HEMT device is used as biological test, need to carry out functional modification on sample cell sensing surface, sample adopts UV/O3 to carry out surface treatment to sample cell sensing surface, is then added drop-wise in sample cell by the toluene solution of the APTES (APTES) of 5%, carries out silanization to sensitive zones surface, after 2h, adopt toluene respectively, deionized water fully rinses, rear employing nitrogen dries up, formed can sessile antibody, DNA molecule film.
In AlGaN/GaN HEMT(High Electron Mobility Transistor) in structure, due to piezoelectricity and spontaneous polarization effect, the interface of AlGaN/GaN HEMT device can form a 2DEG(two-dimensional electron gas) surface channel, 2DEG in potential well is controlled by grid voltage, this structure adopts molecule film to replace as the grid of AlGaN/GaN HEMT during biology sensor, during devices function, the introducing of determined antigen causes the change of molecule film surface voltage, thus cause the change of 2DEG concentration in potential well, and the change of 2DEG concentration can cause the change of electric current between the source electrode (source) of transistor and drain electrode (drain), therefore the change by electric current detects the concentration change introducing determined antigen.
Above-mentioned GaN base biology sensor is utilized to detect prostate specific antigen:
In the sensing chamber of silanization, drip 2.5% glutaraldehyde solution, hydroformylation 1h, adopt deionized water rinsing.After flushing dries up, in sensing chamber, drip the PSA antibody of 10 μ g/ml, seal the interior cultivation of the refrigerator being placed on 4 DEG C 24 hours, carboxyl is fully combined with antibody, after having cultivated, then adopt the bovine serum albumin(BSA) (BSA) of 1% to close avtive spot.
Sensor after sessile antibody, under 50mV constant bias voltage, measures the PSA of 0.1pg/ml, and survey 3 times, average, measurement result as shown in Figure 2.As can be seen from the figure, when test PBS damping fluid and interpolation BSA are to sensitive zones surface, the current signal of device does not all significantly change, and illustrates that sensor has good stability and specificity.When adding concentration and being the PSA of 1pg/ml, the electric current of sensor reduces by 0.473 μ A, this means that PSA there occurs reaction with the antibody in HEMT finishing, and millimeter magnitude device possesses the ability measuring low concentration PSA.
For this device, measure the response of device to the PSA of variable concentrations, often kind of measurement of concetration 3 times, average, measurement result as shown in Figure 3.As can be seen from the figure millimeter magnitude molecule film gate electrode AlGaN/GaN HEMT biology sensor to the detection limit of PSA lower than 0.1pg/ml.This micron dimension gate electrode metal AlGaN/GaN HEMT sensor response to PSA made than people such as B.S.Kang improves 2 orders of magnitude.
Be easy to it is contemplated that in other embodiments, when adopting silicone to encapsulate source electrode and drain electrode, sensing unit also first can form Au film or oxide passivation layer film, then molecule film is modified on Au film or oxide passivation layer film.Same, in the embodiment not adopting Au film or oxide passivation layer film, also can adopt other passivation layers of non-silicone to the encapsulation of device, such as silicon nitride.
It should be noted that, in this article, the such as relational terms of first and second grades and so on is only used for an entity or operation to separate with another entity or operational zone, and not necessarily requires or imply the relation that there is any this reality between these entities or operation or sequentially.And, term " comprises ", " comprising " or its any other variant are intended to contain comprising of nonexcludability, thus make to comprise the process of a series of key element, method, article or equipment and not only comprise those key elements, but also comprise other key elements clearly do not listed, or also comprise by the intrinsic key element of this process, method, article or equipment.When not more restrictions, the key element limited by statement " comprising ... ", and be not precluded within process, method, article or the equipment comprising described key element and also there is other identical element.
The above is only the embodiment of the application; it should be pointed out that for those skilled in the art, under the prerequisite not departing from the application's principle; can also make some improvements and modifications, these improvements and modifications also should be considered as the protection domain of the application.