Summary of the invention
The objective of the invention is at the deficiencies in the prior art, a kind of silica-based optical transmitting set and preparation method thereof is proposed, it improves the silicon-based devices luminous intensity jointly by utilizing photonic crystal nano column array and silicon nanocrystal quantum-dot structure, realizes the lifting of light emission effciency.
For achieving the above object, the present invention has adopted following technical scheme:
A kind of silica-based light emitting devices, comprise silicon substrate, it is characterized in that, described silicon substrate front forms nano-pillar photonic crystal array through etching, conformal deposited contains the thin layer of silicon nanocrystal quantum-dot structure on the described nano-pillar photonic crystal array, cover transparent conformal electrode on the described thin layer, described silicon substrate backside deposition has Ohm contact electrode.
Preferably, described silicon substrate employing resistivity is the B heavy doping P type silicon chip of 0.004~0.005 Ω cm.
Nano-pillar height in the described nano-pillar photonic crystal array is 0.8~3 μ m, and diameter is 100~500nm, and adjacent two nano-pillar centre distances are 300nm~1.5 μ m.
Described thin layer is silicon rich silicon oxide, silicon nitride or the carborundum films that contains the silicon nanocrystal quantum-dot structure, and thickness is 50~300nm.
Described transparent conformal electrode adopts ITO or electroconductive organic film, and thickness is 200~500nm.
Described Ohm contact electrode thickness is 200~1000nm, and simultaneously, described Ohm contact electrode material is any one in aluminium, copper, silver, gold and the platinum or wherein any two kinds and above alloy at least.
The preparation method of silica-based light emitting devices is characterized in that as mentioned above, and this method is:
I, form sequential 2 D SiO in the positive self assembly of the silicon substrate after cleaning
2Nano microsphere colloid monolayer layer;
II, utilize microballoon mask etching technology, obtain silicon nano-pillar photonic crystal array by deep reaction ion etching;
III, conformal growth contains the thin layer and the transparent conformal electrode of nano silicon quantum dots structure on silicon nano-pillar photonic crystal array successively, and deposits Ohm contact electrode on the silicon substrate back side, obtains target product.
Further, adopt<100 in the step I 〉, resistivity be the heavily doped P type of the B of 0.004~0.005 Ω cm silicon chip as substrate, and form sequential 2 D SiO in the substrate face self assembly with czochralski method
2Nano microsphere colloid monolayer layer.
Nano-pillar height in the described nano-pillar photonic crystal array is 0.8~3 μ m, and diameter is 100~500nm, and adjacent two nano-pillar centre distances are 300nm~1.5 μ m.
Adopting in the step II utilizes PECVD or LPCVD technology and subsequent anneal technology conformal growth on silicon nano-pillar photonic crystal array to contain the thin layer of nano silicon quantum dots structure, described thin layer is silicon rich silicon oxide, silicon nitride or carborundum films, and thickness is 50~300nm.
Described transparent conformal electrode adopts ITO or electroconductive organic film, and thickness is 200~500nm.
Described Ohm contact electrode is at least by any one metal in aluminium, copper, silver, gold and the platinum or wherein any two kinds and above alloy composition, its thickness 200~1000nm.
The present invention uses SiO
2Nano microsphere is made mask, its anti-etching can improving a lot by the existing polystyrene microsphere of force rate, the etching technics that uses is a deep reaction ion etching technology, BOSCH technology after particularly optimizing, these technological designs can obtain the longer silicon nano column array of length, thereby can retrain light better in horizontal scattering, improve the light extraction efficiency of vertical direction to a greater extent; And bigger contact area is arranged between nano-silicon post and the conformal thin-film, and this has also improved the injection efficiency of charge carrier simultaneously widely.
More specifically say, the present invention organically combines photonic crystal nano column array and silicon nanocrystal quantum-dot structure in si-based light-emitting device, both modulated optical propagation direction by silicon nano-pillar photonic crystal array, increased light extraction efficiency, its bigger contact area makes the injection efficiency in electronics-hole be greatly improved again simultaneously, and the combination level that being accompanied by intermediate layer silicon nanocrystal quantum dot is provided increases the radiation recombination efficient of charge carrier jointly, thereby has increased light radiation efficient.
Compared with prior art, the present invention has the following advantages at least:
1. the present invention combines photonic crystal nano column array and silicon nanocrystal quantum-dot structure, can increase the injection efficiency and the light extraction efficiency of charge carrier greatly on original basis, thereby enlarge markedly the light emission effciency.
2. utilize the method for the silicon nano column array of Nano microsphere mask etching technology acquisition in the preorder experiment of the present invention, the electron beam lithography means that replaced the required costliness of Nano grade, greatly reduced experiment and production cost, this commercial application to product is a huge advantage.
3. the present invention can utilize the sequential 2 D photonic crystal nano-array for preparing large tracts of land, few defective with the compatible mutually means of semiconductor technologies such as modern CMOS, MEMS; be convenient to the large-scale production of product and the raising of rate of finished products, be convenient to the industrialization link and the popularization of product.
4. operation of the present invention is simple, and feasibility, operability and repeatability are very strong, can produce exemplary role to traditional related industry, promotes industrial upgrading.
The present invention has reference and application study meaning to the development of silicon substrate laser and the fields such as research of light and matter interaction, and also significant in the interconnected and full optical interconnection of silica-based monolithic photoelectricity is used.
Embodiment
Deficiency at existing si-based light-emitting device, this case inventor is through studying for a long period of time and a large amount of practice, technical scheme of the present invention has been proposed, it obtains the nano-pillar photonic crystal array of arrangement in order by the front surface dry etching at heavily doped P type silicon substrate, and this above array conformal deposited and annealing obtain to contain the thin layer of silicon nanocrystal quantum-dot structure, on film, form transparent conformal electrode then, and Ohm contact electrode is arranged, thereby obtained the novel silicon base light emitting devices at the silicon substrate backside deposition.
Preferably, aforementioned nano-pillar is of a size of high 0.8~3 μ m, diameter 100~500nm, and adjacent two nano-pillar centre distances are 300nm~1.5 μ m;
The thickness of aforementioned thin layer is 50~300nm, and it can be silicon rich silicon oxide, silicon nitride, carborundum films etc., but is not limited thereto.
The thickness of aforementioned transparency electrode is 200~500nm, and it can be tin indium oxide (ITO) or electroconductive organic film (as the P3HT film), but is not limited thereto.
Aforementioned silicon substrate back side Ohm contact electrode can by or aluminium (Al) or copper (Cu) or silver (Ag) or gold (Au) or platinum metals such as (Pt) make, also can make jointly by multiple metal material, the for example copper electrode of electroplate or copper nickel, aluminium nickel, cr-au electrode etc., its thickness is 200~1000nm.
The preparation method of foregoing silicon substrate light emitting devices can comprise following processing step:
(1) right<100 〉, resistivity is that the P type silicon chip of the heavy doping (as, B heavy doping) of 0.004~0.005 Ω cm cleans;
(2) utilize the microballoon self assembly to form the few defective sequential 2 D SiO of large tracts of land by czochralski method
2Nano microsphere colloid monolayer layer;
(3) utilize microballoon mask etching technology, obtain silicon nano-pillar photonic crystal array by deep reaction ion etching;
(4) utilize PECVD or LPCVD and the conformal growth of subsequent anneal technology to contain the thin layer of nano silicon quantum dots structure;
(5) the conformal growth of transparency electrode;
(6) deposition of silicon base back of the body Ohmic electrode.
Above-mentioned czochralski method is similar to the LB embrane method, can be by regulating SiO
2The concentration of the particle diameter of microballoon, quality, microballoon suspension-turbid liquid and pull rate obtain the individual layer Nano microsphere colloid layer of required orderly arrangement.Such as, preferred scheme is to be the SiO of 150nm~750nm with the diameter
2Nano microsphere is dispersed in the ethanol/water, forms 1%~10% (V%) suspension-turbid liquid; The condition of czochralski method is: pull rate: 2~50 μ m/s; Lift temperature: room temperature; Lift humidity: 30%~50%.
Above-mentioned deep reaction ion etching is 13.56MHz in the power source frequency preferably, and base reservoir temperature is carried out in-3~0 ℃ the STS deep reaction ion etching machine, and it is with C
4F
8, SF
6, O
2Be the etching source of the gas,, can regulate the diameter and the height of nano column array by regulating ratio, etching power, radio-frequency power and the etch period between etch mode, the different source of the gas.Wherein a kind of comparatively preferred process conditions are: concrete etching condition is as follows: etching technics: BOSCH technology; Etching source of the gas, flow and time: SF
620~30sccm 4s, O
220~50sccm 4s, C
4F
820~50sccm 4s; Etching power: 400~1000W; Radio-frequency power: 40~70W; Reaction chamber pressure: 4~10mTorr; Etching total time: 4~10min.
The technical process that the conformal growth of above-mentioned PECVD or LPCVD method obtains film is, is example with the PECVD method growth technique of silicon rich silicon oxide film, is 13.56MHz in the power source frequency preferably, and substrate temperature is to obtain under the operating pressure of 350 ℃ and 2000mTorr.It is with SiH
4, N
2O, Ar are source of the gas, by regulating ratio, deposition pressure, the sedimentation time between the different sources of the gas, can regulate the component and the thickness of silicon rich silicon oxide film.Wherein a kind of condition of comparatively selection process is: sedimentary condition is as follows: deposition gas and flow: SiH
43~55sccm; N
2O 710sccm; Ar 180sccm; Radio-frequency power: 20W; Reaction chamber pressure: 2000mTorr.
Above-mentioned subsequent anneal technology is preferably at N
2Protection under carry out, earlier carry out dehydrogenation and handle at 400~500 ℃, carry out insulation annealing at 800~1300 ℃ respectively then and handle, thereby can obtain the silicon nanocrystal quantum-dot structure of different size.Subsequent anneal technology with the silicon rich silicon oxide film is example, and wherein a kind of condition of comparatively selection process is: at N
2Protection under; sample is warming up to 400~500 ℃ also is incubated about half an hour in annealing furnace to reach the purpose of dehydrogenation; also insulation is about partly to one hour to continue to be warming up to 800~1300 ℃ then, thereby the silicon nanocrystal quantum dot can be separated out equably, and then is cooled to room temperature naturally.
The conformal growth of above-mentioned tin indium oxide (ITO) electrode is preferably carried out on the ito thin film evaporator, is under the environment of 280~350 ℃ and oxygen in temperature, and by regulating the evaporation time, but evaporation goes out the ITO conductive film electrode that thickness is 200~500nm.And if adopt electroconductive organic film as transparent conformal electrode, then it can adopt the known prepared in various methods of those skilled in the art to form.
The deposition of above-mentioned silicon base back of the body Ohmic electrode is preferably carried out in the electron beam evaporation system, by changing deposition power, sedimentation time, can obtain the Ohm contact electrode of different-thickness.
Reach a wherein preferred embodiment below in conjunction with accompanying drawing and describe technical scheme of the present invention in detail:
The basic structure of the silica-based light emitting devices of present embodiment can be with reference to shown in Figure 1: in resistivity is the nano-pillar photonic crystal array 2 that the front surface of the heavily doped P type of the B silicon substrate 1 of 0.004~0.005 Ω cm has the orderly arrangement that dry etching obtains, the silicon rich silicon oxide film 3 that contains the silicon nanocrystal quantum-dot structure that has conformal deposited and annealing to obtain above the array also has the conformal electrode 4 of indium oxide layer tin (ITO) then on it; At the silicon substrate backside deposition Ohm contact electrode 5 is arranged.
The preparation technology of this silica-based light emitting devices is as follows:
1) adopt<100 〉, resistivity is that the heavily doped P type of the B of 0.004~0.005 Ω cm silicon chip is as substrate.
2) silicon chip is cleaned, comprise organic washing and inorganic matting;
3) preparation of mask colloid layer: by czochralski method, utilize the capillary force that meniscus produces between the Nano microsphere to be main drive, the two-dimentional SiO of the orderly self assembly of preparation large tracts of land individual layer on silicon chip
2The Nano microsphere colloid layer, as shown in Figure 2.
Wherein actual conditions is as follows: pull rate: 25 μ m/s; Lift temperature: room temperature; Lift humidity: 45%; Microspherulite diameter: 500nm; Suspension-turbid liquid: SiO
2The ethanol/water suspension-turbid liquid of Nano microsphere; Suspension-turbid liquid concentration: 5% (V%).
4) deep reaction ion etching of silicon nano-pillar photonic crystal: the microballoon colloid layer that forms with self assembly is a mask, and surface of silicon is carried out deep reaction ion etching.By changing different etching conditions, obtain the orderly photonic crystal array of silicon nano-pillar of different-shape and size, as shown in Figure 3.Used instrument is Oxford Systems Plasma Lab 380s.
Wherein concrete etching condition is: etching technics: BOSCH technology; Etching source of the gas, flow and time: SF
625sccm 4s, O
230sccm 4s, C
4F
845sccm 4s; The power source frequency is: 13.56MHz; Power is: 700W; Radio-frequency power: 50W; Reaction chamber pressure: 10mTorr; Etching total time: 7min.
After silicon nano-pillar etching is finished, need the original SiO of erosion removal
2The mask microballoon.Remove the used solution formula of mask microballoon: HF: deionization H
2O=1:10, corrosion temperature are normal temperature, etching time 3~5min.The silicon nano-pillar diameter that is obtained is about 300nm, and length is 1.5~2 μ m.
5) contain the preparation of the silicon rich silicon oxide thin layer of silicon nanocrystal quantum-dot structure: utilize plasma enhanced chemical vapor deposition (PECVD) technology, on the silicon nano column array basis that has prepared, the silicon rich silicon oxide film of the about 100nm of conformal growth one layer thickness.Pass through certain annealing process then, obtain the required silicon rich silicon oxide film that contains silicon nanocrystal.
Wherein, the concrete process conditions of film growth are among the PECVD: deposition gas and flow: SiH
440sccm, N
2O 710sccm, Ar 180sccm; Power source frequency: 13.56 MHz; Radio-frequency power: 20W; Reaction chamber pressure: 2000mTorr; Underlayer temperature: 350 ℃.
The annealing process actual conditions is: preceding prepared sample is put into annealing furnace under the room temperature, be warming up to 400 ℃ and also be incubated about half an hour to reach the purpose of dehydrogenation, continue to be warming up to 800~1300 ℃ then and also be incubated half an hour approximately, thereby the silicon nanocrystal quantum dot can be separated out equably, and then be cooled to room temperature naturally and get final product, whole annealing process needs N
2Gas is protected.
6) preparation of top and bottom electrode:
The preparation of upper electrode: the device after will annealing is put on the ito thin film evaporator, is that evaporation thickness is the ITO conductive membrane layer of 150nm under the environment of 280~350 ℃ and oxygen in temperature.
The preparation of silicon bottom Ohm contact electrode: utilize the electron beam evaporation system, at silicon substrate backside deposition Ohm contact electrode, thickness is 200~400nm.
The present invention need not electron beam lithography at nanoscale, has increased the injection efficiency and the light extraction efficiency of charge carrier when greatly saving cost again, follows the silicon nanocrystal structure can improve luminous intensity jointly, can be used for the research preparation of silicon substrate laser etc.Device preparation technology is simple, and parameter is accurately adjustable, and is compatible mutually with the silicon technology of existing maturation, also significant in the interaction of the application of micro-nano optoelectronic areas and research light and material to promoting the photonic crystal nano column array simultaneously.
In addition to the implementation, the present invention can also have other execution mode.The technical scheme that all employing equivalent transformations or be equal to replace to form (for example changes the type of substrate and doping content, SiO
2The diameter of Nano microsphere, etching actual conditions etc.), all within the protection range that the present invention requires.