The device architecture and the preparation method of grid modulation formal dress structure GaN base light emitting diode
Technical field
The present invention is used for semiconductor photoelectronic device manufacturing technology field, is specifically related to device architecture and preparation method that a kind of novel grid is modulated the GaN based light-emitting diode.
Background technology
The GaN base semiconductor is novel broad stopband direct gap semiconductor material, has excellent physics, chemical property.Great power LED based on the InGaN quantum well structure is the focus and the related industry development tap of current semi-conductor photoelectronic research field.Current I II group-III nitride shows at colour, the decorative illumination lamp numerous areas has obtained extensive use.
The quantum well radiation structure is the prominent example that quantum physics is used at optoelectronic areas, after quantum well thickness is reduced to nanometer scale, the stepped distribution of the charge carrier density of states, thereby under identical injection level, easier realization electronics, hole-recombination, obtain Wavelength stabilized, the light emission spectrum that spectral line is narrower.Yet the III group-III nitride of pricker zinc ore structure has hexagonal crystallographic texture, and its symmetry has very strong spontaneous polarization field not as good as cube crystal phase structure; With traditional GaAs system quantum well structure comparison, there is bigger lattice mismatch between the InGaN/GaN system in addition, under the effect of crystal lattice stress, causes stronger piezoelectric polarization electric field, can reach MV/cm usually, cause significant quantum limit Stark effect.Under the polarized electric field effect, conduction band electron separates with valence band hole wave function space in the quantum well, and electronics, hole-recombination probability reduce, thereby reduces radiation recombination efficient.In addition, influenced by polarity effect, increase with injection current, the LED emission wavelength is offset, and can reach 3-5nm usually.The drift of emission wavelength will produce following problem in actual applications: aspect demonstration, wavelength change will cause full color to show very difficulty of control, and the too wide meeting of spectrum simultaneously causes color impure; In the white-light illuminating field, because the variation of blue light wavelength will cause the color of white light or colour temperature to change.
Before the present invention,, utilize means such as lattice match quantum well structure or non-polar plane growth to reduce polarity effect, but effect is unsatisfactory usually by optimizing epitaxial growth.
Summary of the invention
The preparation method who the object of the present invention is to provide a kind of novel grid to modulate the device architecture of formal dress structure GaN base light emitting diode.This structure is utilized extra electric field by gate insulator medium and gate electrode, and balance InGaN/GaN system is because spontaneous polarization, polarized electric field that piezoelectric polarization produced.Reduce the influence of polarity effect, realize the modulation of gate electrode the GaN base LED characteristics of luminescence to device property.The present invention is for reducing III group-III nitride luminescent device polarity effect, and preparation is efficient, and having good consistent wavelength GaN base LED provides a kind of effective way.
Technical scheme of the present invention is as follows:
The invention provides a kind of grid modulation formal dress structure GaN base light emitting diode structure, comprising:
One Sapphire Substrate;
One n type GaN layer, this n type GaN layer is produced on the Sapphire Substrate, and the side above this n type GaN layer is formed with a table top, and the degree of depth of this table top is less than the thickness of n type GaN layer;
One multiple quantum well active layer, this multiple quantum well active layer do not have on the opposite side of table top above being produced on n type GaN layer;
One p type GaN layer, this p type GaN layer is produced on the multiple quantum well active layer;
One P electrode, this p electrode are produced on above the p type GaN layer side away from table top;
One N electrode, this N electrode are produced on the table top above the n type GaN layer;
One gate insulator, this gate insulator are produced on the opposite side that does not have the P electrode above the p type GaN layer;
One gate electrode, this electrode is produced on the gate insulator.
Wherein the material of gate insulator is SiO
2, SiN or SiON, thickness is 0.001-0.1um.
Wherein gate electrode is metal electrode or transparency conductive electrode, and this gate electrode can be realized the modulation to GaN radical luminescence diode characteristic.
The invention provides the preparation method of a kind of grid modulation formal dress structure GaN base light emitting diode structure, comprising following steps:
Step 1: growing n-type GaN layer, multiple quantum well active layer and p type GaN layer successively on the Sapphire Substrate;
Step 2: adopt the method for dry etching, downward etching from the p type GaN layer makes the one side form table top, and etching depth arrives within the n type GaN layer;
Step 3: the side away from table top on p type GaN layer prepares the P electrode;
Step 4: preparation N electrode on table top;
Step 5: on p type GaN layer, do not have the opposite side of P electrode to prepare gate insulator;
Step 6: on gate insulator, prepare gate electrode, finish the making of formal dress structure devices.
Wherein gate insulator is that the material of gate insulator is SiO by deposition or sputter preparation
2, SiN or SiON.
Wherein the thickness of gate insulator is 0.001-0.1um.
Wherein gate electrode is to utilize photoetching, the preparation of band glue stripping technology, and gate electrode is metal electrode or transparency conductive electrode, and this gate electrode 8 can be realized the modulation to GaN radical luminescence diode characteristic.
Wherein the thickness of p type GaN layer is 0.01-0.5um.
Description of drawings
For further specifying content of the present invention, below in conjunction with concrete execution mode the present invention is done detailed description, wherein:
Fig. 1 is the generalized section of GaN based power type LED epitaxial material, adopts the method growth n-GaN layer 2 of extension on Sapphire Substrate 1, active layer 3, p-GaN layer 4;
Fig. 2 is the structure GaN-based LED structural representation of formal dress that utilizes epitaxial material preparation shown in Figure 1, p-GaN layer 4 surface preparation p electrode 5, table top 21 surface preparation n electrodes 6.
Fig. 3 is by deposition or sputters on the positive assembling structure led chip p-GaN layer 4 shown in Figure 2, the schematic diagram of preparation gate insulator 7.
Fig. 4 is the schematic diagram of preparation gate electrode 8 on the structure GaN-based LED gate insulator 7 of formal dress shown in Figure 2.
Embodiment
See also shown in Figure 4ly, the invention provides a kind of grid modulation GaN based light-emitting diode structure, comprising:
One Sapphire Substrate 1;
One n type GaN layer 2, this n type GaN layer 2 is produced on the Sapphire Substrate 1, and the side above this n type GaN layer 2 is formed with a table top 21, and the degree of depth of this table top 21 is less than the thickness of n type GaN layer 2;
One multiple quantum well active layer 3, this multiple quantum well active layer 3 do not have on the opposite side of table top 21 above being produced on n type GaN layer 2, and this layer structure can play restriction to injecting charge carrier, inject charge carrier can be in this one deck recombination luminescence;
One p type GaN layer 4, this p type GaN layer 4 is produced on the multiple quantum well active layer 3, and the thickness of this p type GaN layer 4 is 0.01-0.5um;
One P electrode 5, this p electrode 5 are produced on p type GaN layer 4 a top side away from table top 21;
One N electrode 6, this N electrode 6 are produced on the table top 21 above the n type GaN layer 2;
One gate insulator 7, this gate insulator 7 are produced on the opposite side that does not have P electrode 5 above the p type GaN layer 4, and the material of this gate insulator 7 is SiO
2, SiN or SiON, the thickness of this gate insulator 7 is 0.001-0.1um, by this layer structure, utilizes extra electric field, balance InGaN/GaN system is because spontaneous polarization, polarized electric field that piezoelectric polarization produced.Reduce the influence of polarity effect, realize the modulation of gate electrode, comprise the modulation of emission wavelength, the modulation of luminous intensity etc. the GaN base LED characteristics of luminescence to device property;
One gate electrode 8, this electrode 8 is produced on the gate insulator 7, and this gate electrode 8 is metal electrode or transparency conductive electrode.
See also Fig. 1 to shown in Figure 4, the invention provides a kind of preparation method of grid modulation GaN based light-emitting diode structure, comprising following steps:
Step 1: growing n-type GaN layer 2, multiple quantum well active layer 3 and p type GaN layer 4 successively on the Sapphire Substrate 1, the thickness of this p type GaN layer 4 is 0.01-0.5um;
Step 2: adopt the method for dry etching, etching downwards from the p type GaN layer 4 makes the one side form table top 21, and etching depth arrives within the n type GaN layer 2;
Step 3: the side away from table top 21 on p type GaN layer 4 prepares P electrode 5, and its electrode metal system is that transparency conductive electrode adds NiAgNiAu, NiAgPtAu, NiAgNiAu etc.;
Step 4: preparation N electrode 6 on table top 21;
Step 5: do not have the opposite side of P electrode 5 to prepare gate insulator 7 on p type GaN layer 4, this gate insulator 7 is that the material of gate insulator 7 is SiO by deposition or sputter preparation
2, SiN or SiON, the thickness of this gate insulator 7 is 0.001-0.1um;
Step 6: preparation gate electrode 8 on gate insulator 7, this gate electrode 8 is to utilize photoetching, the preparation of band glue stripping technology, gate electrode 8 is metal electrode or transparency conductive electrode, by this gate electrode 8 is applied voltage signal, realization is finished the making of grid modulation formal dress structure devices to the modulation of GaN radical luminescence diode characteristic.
The above; only be the embodiment among the present invention, but protection scope of the present invention is not limited thereto, anyly is familiar with the people of this technology in the disclosed technical scope of the present invention; the conversion that can expect easily or replacement all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection range of claims.