CN115692579A - Photoelectric conversion device and preparation method thereof - Google Patents
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Abstract
The application provides a photoelectric conversion device based on semiconductor photoelectric effect and a manufacturing method thereof. The photoelectric conversion device includes: a PN junction layer; a reflective layer, wherein a random rough interface layer having a randomly distributed concave-convex pattern generated using a computer random function is disposed between the PN junction layer and the reflective layer. According to the photoelectric conversion device and the manufacturing method thereof, the random rough interface layer is arranged between the PN junction layer and the reflection layer, and the random distribution concave-convex patterns are generated on the random rough interface layer by using the random function of the computer, so that the optimal reflection effect can be generated on photons with any incident angle, and the photoelectric or electro-optical conversion efficiency of the photoelectric conversion device is greatly improved.
Description
Technical Field
The present disclosure relates to the field of semiconductor manufacturing technologies, and in particular, to a photoelectric conversion device based on a semiconductor photoelectric effect and a method for manufacturing the same.
Background
For photoelectric conversion devices based on semiconductor photoelectric effect, such as light emitting diodes, lasers, solar cells, photodetectors, and the like, photoelectric conversion or photoelectric conversion efficiency is the most central device performance index. Taking a light emitting diode as an example, the electro-optic conversion efficiency mainly consists of three parts, namely the electron injection efficiency, the quantum efficiency of converting electrons into photons inside the device and the light guide efficiency of leading the photons out of the device. Under a proper current density, the electron injection efficiency can reach more than 80 percent through an electron-hole barrier limiting layer structure. In a compound semiconductor device composed of direct band gap materials, a heterojunction or a limit structure such as a quantum well, a quantum wire, a quantum dot and the like is adopted, and the quantum efficiency of converting electrons in the device into photons can reach more than 90%. Because the semiconductor of the photoelectric device and air have great difference of optical refractive index, the semiconductor is about 3.5, the air or vacuum is 1, and the light has total reflection phenomenon on the interface of the semiconductor and the air. At a perfectly flat semiconductor/air interface, less than 2% of the light within the optoelectronic device can be directed out of the device interior. Therefore, the light extraction efficiency becomes a bottleneck of the overall photoelectric conversion efficiency of the light emitting device.
In order to improve light extraction efficiency, roughening of the light reflecting interface in the semiconductor is generally required. Chemical etching is usually performed on the surface of a semiconductor by using a chemical solution, for example, a silicon solar cell is subjected to surface roughening by using a mixed solution of hydrofluoric acid and nitric acid, and a silicon semiconductor with the surface about 10 microns needs to be consumed; the red light LED chip adopts strong corrosion solution to coarsen the surface of the GaP layer on the surface, and the thickness of the GaP layer is required to be more than 5 micrometers; the blue light LED chip adopts photoetching to form a regular pss (patterned sapphire substrate) pattern back coarsening substrate, and because the photon direction generated by the spontaneous radiation recombination of the photoelectric device is random and is uniformly distributed in a 360-degree solid angle, the regular pattern can only generate the optimal reflection effect on the photons at a specific angle and cannot reach the optimal value of the integral reflection.
Disclosure of Invention
The invention mainly aims to provide a photoelectric conversion device based on semiconductor photoelectric effect and a manufacturing method thereof, so as to greatly improve the photoelectric or electro-optical conversion efficiency of the photoelectric conversion device.
A first aspect of the present invention provides a photoelectric conversion device including:
a PN junction layer;
a reflective layer, which is disposed on the substrate,
wherein a random rough interface layer is arranged between the PN junction layer and the reflecting layer, and the random rough interface layer is provided with a randomly distributed concave-convex pattern generated by a random function of a computer.
According to one embodiment of the present invention, the random rough interface layer is formed on the PN junction layer.
According to one embodiment of the present invention, an additional functional layer is provided between the PN junction layer and the reflective layer, and a random rough interface layer is formed on the additional functional layer.
According to an embodiment of the present invention, the photoelectric conversion device is a device for converting electric energy into optical energy, and the PN junction layer sequentially includes, in a direction away from the reflective layer:
a first conductive layer;
a first current confinement layer;
a light emission functional layer;
a second current confinement layer;
a second conductive layer;
wherein the random rough interfacial layer is disposed between the first conductive layer and the reflective layer.
According to one embodiment of the present invention, the random rough interface layer is formed on the first conductive layer.
According to one embodiment of the invention, the random rough interface layer is formed on an additional functional layer between the first conductive layer and the reflective layer.
According to an embodiment of the present invention, the photoelectric conversion device is a device for converting light energy into electric energy, and the PN junction layer sequentially includes, in a direction away from the reflective layer:
a first conductive layer;
a first current confinement layer;
a light absorbing functional layer; a second current confinement layer;
a second conductive layer;
wherein the random rough interfacial layer is disposed between the first conductive layer and the reflective layer.
According to one embodiment of the present invention, the random rough interface layer is formed on the first conductive layer.
According to one embodiment of the invention, the random rough interface layer is formed on an additional functional layer between the first conductive layer and the reflective layer.
An embodiment of another aspect of the present invention provides a method of manufacturing a photoelectric conversion device, including:
preparing a PN junction layer;
preparing a random rough interface layer on the backlight side of the PN junction layer, wherein the random rough interface layer is provided with a randomly distributed concave-convex pattern generated by a random function of a computer;
and forming a reflecting layer on the random rough interface layer.
According to one embodiment of the invention, preparing the random rough interface layer on the backlight side of the PN junction layer comprises:
generating a two-dimensional random distribution coordinate by using a computer random function;
preparing a photoetching mask plate according to a two-dimensional random distribution coordinate generated by a computer random function; and
and preparing a random rough interface layer on the backlight side of the PN junction layer by using the photoetching mask.
According to one embodiment of the invention, the preparation of the random rough interface layer on the backlight side of the PN junction layer by using the photoetching mask comprises the following steps:
forming a two-dimensional random distribution pattern on the backlight side of the PN junction layer by photoetching by using the photoetching mask; and
and etching the two-dimensional randomly distributed pattern to form a three-dimensional randomly distributed concave-convex pattern.
According to one embodiment of the present invention, the depth of the grooves in the three-dimensional randomly distributed concave-convex pattern is 1d to 2d, wherein d =10 × lenda/n, where lenda is the wavelength of light in vacuum and n is the refractive index of the semiconductor at that wavelength.
According to an embodiment of the present invention, the generating two-dimensional randomly distributed coordinates using a computer random function includes:
determining the exposure area d of each exposure point 2 D =10 × lenda/n; where lena is the wavelength of light in vacuum and n is the refractive index of the semiconductor at that wavelength;
the number a x b of random numbers to be generated on each chip unit is calculated, wherein,
a is the number of random points required to be generated in the X direction, b is the number of random points required to be generated in the Y direction, S is an exposure factor, namely the ratio of the exposure area to the total area, X is the width of one chip unit, and Y is the length of one chip unit;
according to the required number a multiplied by b of random numbers, exposure coordinates (x, y) of the lithography mask are generated by using a computer random function, wherein 0-type and x-type and 0-type and y-type are combined.
According to one embodiment of the present invention, the chip unit is a basic unit of a photoelectric conversion device.
According to an embodiment of the present invention, the generating two-dimensional randomly distributed coordinates using a computer random function includes:
dividing the chip basic unit into m × n regions, each region having a width of X/m and a length of Y/n,
determining the exposure area d of each exposure point 2 D =10 × lenda/n; where lena is the wavelength of light in vacuum and n is the refractive index of the semiconductor at that wavelength;
the number a x b of random numbers to be generated on each chip area is calculated, wherein,
a is the number of random points required to be generated in the X direction, b is the number of random points required to be generated in the Y direction, S is an exposure factor, namely the ratio of the exposure area to the total area, X is the width of one chip unit, and Y is the length of one chip unit;
and generating exposure coordinates (x, y) of the lithography mask by utilizing a computer random function according to the number a1 × b1 of the random numbers, wherein the 0-yarn x-yarn X/m and the 0-yarn y-yarn Y/n are formed.
According to an embodiment of the present invention, wherein,
or alternatively
The preparation precision of the photoetching mask is sigma).
According to the photoelectric conversion device and the manufacturing method thereof, the random rough interface layer is arranged between the PN junction layer and the reflection layer and is provided with the randomly distributed concave-convex patterns generated by the random function of the computer, so that the random rough interface layer has the randomly distributed reflection angles, the optimal reflection effect can be generated on photons with any incidence angles, and the photoelectric or electro-optic conversion efficiency of the photoelectric conversion device is greatly improved.
Drawings
Fig. 1 is a schematic view of the overall structure of a photoelectric conversion device according to an embodiment of the present invention.
Fig. 2 is a schematic plan view of the randomly rough interfacial layer of fig. 1.
Fig. 3 is a flowchart of a method of manufacturing a photoelectric conversion device according to an embodiment of the present invention.
Fig. 4 is a flowchart of the detailed steps of preparing the random rough interfacial layer in step S2 of fig. 3 according to an embodiment of the present invention.
Fig. 5 is a flowchart of the detailed steps of using a photolithographic mask to prepare a random rough interfacial layer in step S23 of fig. 4 according to one embodiment of the present invention.
Fig. 6 is a flowchart illustrating specific steps of generating two-dimensional randomly distributed coordinates using a computer random function in step S21 of fig. 4 according to an embodiment of the present invention.
Fig. 7 is a schematic structural diagram of a light emitting diode according to an embodiment of the invention.
Fig. 8 is a structural diagram illustrating a process of manufacturing the light emitting diode of fig. 7.
Fig. 9 is an enlarged cross-sectional view of the randomly rough interfacial layer of fig. 7.
Fig. 10 shows a schematic diagram of the light path in the light emitting diode of fig. 7.
Fig. 11 is a schematic structural view of a solar photovoltaic cell according to another embodiment of the present invention.
Fig. 12 shows a schematic diagram of the light path in the solar photovoltaic cell of fig. 11.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention. In the embodiments of the present invention and the drawings, the same reference numerals denote the same meanings unless otherwise defined. It is noted that for clarity, the drawings of the embodiments may not necessarily be to scale; in addition, the drawings of the embodiments are only schematic structures, and some conventional structures which are not directly related to the idea of the invention may be omitted; also, it should be noted that the order of the method steps described in the embodiments of the present invention does not necessarily indicate an actual execution order of the respective steps. Where feasible, the actual order of execution may differ from that described.
Fig. 1 is a schematic view of the overall structure of a photoelectric conversion device according to an embodiment of the present invention. As shown in fig. 1, according to the present general inventive concept, a photoelectric conversion device 10 includes a PN junction layer 100 and a reflective layer 200, wherein a random rough interface layer 300 is disposed between the PN junction layer 100 and the reflective layer 200, the random rough interface layer 300 having a randomly distributed concave-convex pattern generated using a computer random function. Note that fig. 1 schematically illustrates only a part of the structural layers of the photoelectric conversion device related to the inventive concept, and those skilled in the art will understand that the photoelectric conversion device 10 may further include other known structural layers, for example, an electrode layer, a transmission film, etc., and the present invention is not limited thereto. In addition, the thickness of the interface layer is shown exaggerated for clarity.
The photoelectric conversion device of the present invention may be a semiconductor device that converts electricity into light, such as a light emitting diode, or may be a device that converts light into electricity, such as a solar photovoltaic cell or a laser detector. In a semiconductor device that converts electricity into light, a PN junction layer serves as a light emitting layer that converts an externally input electrical signal into an optical signal, and a reflective layer that reflects the generated light to the outside of the device. In a device for converting light into electricity, a PN junction layer serves as a light absorbing layer, a reflective layer reflects light inputted from the outside inside the device, and the PN junction layer absorbs the light to generate an electric signal.
Fig. 2 is a schematic plan view of the random rough interface layer 300 of fig. 1, showing a randomly distributed concave-convex pattern of the surface of the random rough interface layer 300. The method for generating the randomly distributed concave-convex pattern is to prepare a random rough interface layer on the backlight side (back-to-air interface side a) of the PN junction layer 100, and specifically includes: generating a two-dimensional random distribution coordinate by using a computer random function; preparing a photoetching mask plate according to a two-dimensional random distribution coordinate generated by a computer random function; and in the process of manufacturing the photoelectric conversion device 10, after the PN junction layer 100 is prepared, a random rough interface layer 300 is prepared on the backlight side of the PN junction layer 100 by using the photolithography mask, thereby obtaining a surface having a randomly distributed concave-convex pattern.
Here, the random rough interface layer 300 may be a concave-convex pattern formed directly on the PN junction layer 100 by photolithography and etching, that is, the surface of the PN junction layer 100 adjacent to the reflective layer 200 is made into a concave-convex surface as an interface layer. Alternatively, an additional functional layer, such as a micron-sized organic layer, may be separately formed between the PN junction layer 100 and the reflective layer 200, and photolithography and etching are performed on the surface of the organic layer to prepare a concave-convex pattern as a random rough interface layer, which is not limited in the present invention. After the random rough interface layer 300 is formed on the PN junction layer 100, one or more layers of a material having high reflectivity, for example, a metal such as Ag, al, au, or other optical structures having high reflectivity, such as a bragg reflector (DBR) or the like, may be coated on the random rough interface layer 300 as the reflective layer 200 by a known plating method. Alternatively, before the reflective layer is formed, a high-transmittance film including an oxide film, a sulfide film, an organic film, or the like may be deposited by evaporation.
In the photoelectric conversion device with the structure, the random rough interface layer is arranged between the PN junction layer and the reflection layer, and the random rough interface layer has the randomly distributed concave-convex patterns generated by utilizing the random function of the computer, and the reflection angles are randomly distributed, so that the optimal reflection effect can be generated on photons with any incidence angle, and the photoelectric or electro-optical conversion efficiency of the photoelectric conversion device is greatly improved. Meanwhile, a random rough interface layer with randomly distributed concave-convex patterns is prepared by adopting a photoetching method, and the thickness of the interface layer can be accurately controlled within 2 microns, so that the thickness of the semiconductor material can be reduced, and the material cost is reduced.
Fig. 3 is a flowchart of a method of manufacturing a photoelectric conversion device according to an embodiment of the present invention. As shown in fig. 3, the method for manufacturing the photoelectric conversion device includes the steps of:
s1, preparing a PN junction layer;
s2, preparing a random rough interface layer on the backlight side of the PN junction layer, wherein the random rough interface layer is provided with a randomly distributed concave-convex pattern generated by a random function of a computer;
and S3, forming a reflecting layer on the random rough interface layer.
Specifically, as shown in fig. 4, according to one embodiment, the step S2 of preparing the random rough interface layer on the backlight side of the PN junction layer comprises:
s21, generating a two-dimensional random distribution coordinate by using a computer random function;
s22, preparing the photoetching mask plate according to the two-dimensional random distribution coordinates generated by the random function of the computer; and
s23, preparing a random rough interface layer on the backlight side of the PN junction layer by using the photoetching mask.
In step S23, as shown in fig. 5, the preparing a random rough interface layer on the backlight side of the PN junction layer by using the photolithography mask includes:
s231, forming a two-dimensional random distribution pattern on the backlight side of the PN junction layer by photoetching through the photoetching mask; and
and S232, etching according to the two-dimensional random distribution pattern to form a three-dimensional random distribution concave-convex pattern.
Here, the etching may be dry etching or wet etching, and the etching depth is 1 to 2d depths, where d =10 × lenda/n, and lenda is the wavelength of light in vacuum; n is the refractive index of the semiconductor at that wavelength.
Further, the included angle between the side wall and the bottom surface of the groove in the formed three-dimensional random distribution concave-convex pattern is 45 degrees to 135 degrees, and preferably 60 degrees. Specifically, the dry etching control realizes that the included angle between the side surface and the bottom surface of the groove deviates from a right angle, generally about 60 degrees, by changing the solution ratio and the temperature, so as to achieve the optimal reflection effect.
According to an embodiment, as shown in fig. 6, in step S21, generating two-dimensional randomly distributed coordinates by using a computer random function may specifically include:
s211, determining the exposure area d of each exposure point 2 D =10 × lenda/n; where lenda is the wavelength of light in vacuum and n is the refractive index of the semiconductor at that wavelength; (why is 10 × lenda/n, i feel necessary to explain the following reason)
S212, the number a × b of the random numbers to be generated on each chip unit is calculated, wherein,
a is the number of random points required to be generated in the X direction, b is the number of random points required to be generated in the Y direction, s is an exposure factor, namely the ratio of the exposure area to the total area, X is the width of one chip unit, and Y is the length of one chip unit;
s213, generating exposure coordinates (x, y) of the lithography mask by using a computer random function according to the number a x b of the random numbers, wherein the layers of 0- < x- < > X and the layers of 0- < y- < > Y.
Repeating the above process to obtain random coordinates corresponding to the whole chip.
Here, the random number generation employs a uniform distribution algorithm (uniform distribution), a more advanced beta distribution random algorithm may also be employed, orOther advanced random number generation algorithms. Based on the above random numbers, the coordinates of each exposure point are (a, b), and assuming that each exposure point is a minute square, the exposure point area d 2 Thereby generating a global random pattern.
Optionally, according to another embodiment, as shown in fig. 6, in step S21, generating two-dimensional randomly distributed coordinates by using a computer random function specifically includes:
s210, dividing the chip basic unit into m × n chip areas, wherein the width of each area is X/m, the length of each area is Y/n,
s211', determining the exposure area d of each exposure point 2 D =10 × lenda/n; where lena is the wavelength of light in vacuum and n is the refractive index of the semiconductor at that wavelength;
s212', the number a1 × b1 of random numbers to be generated on each chip area is calculated, wherein,
a1 is the number of random points to be generated in the X direction, b1 is the number of random points to be generated in the Y direction, S is the exposure factor, i.e., the ratio of the exposure area to the total area, X is the width of one chip unit, and Y is the length of one chip unit.
According to this embodiment, the chip basic unit is divided into m × n regions according to actual needs, each region has a width of X/m and a length of Y/n, and random patterning is performed on each region of m × n according to the aforementioned algorithm, thereby further providing uniformity of random distribution.
S213', generating exposure coordinates (x, y) of the lithography mask by using a computer random function according to the number a x b of the random numbers, wherein the layers of 0- < x < > are formed by X/m, and the layers of 0- < y < > are formed by Y/n.
Preferably, make
Or
Wherein the sigma is the preparation precision of the photoetching mask. When it is satisfied withUnder the boundary condition, the size of the photoetching pattern is sigma-corrected and is a random process, so that a natural random process is introduced. I.e. when
Or
In time, due to the independent randomness of the photolithographic lapping plate preparation process, uniformly distributed random patterns can be generated, and sources of randomness include random variations in mechanical structures and random disturbances to the optical propagation process.
According to the method for manufacturing the photoelectric conversion device of the embodiment, the random rough interface layer is prepared on the backlight side of the PN junction layer, the random rough interface layer is provided with the randomly distributed concave-convex pattern generated by the random function of the computer, and the reflection layer is formed on the random rough interface layer, so that the optimal reflection effect can be generated on photons with any incident angle, and the photoelectric or electro-optical conversion efficiency of the photoelectric conversion device is greatly improved. Meanwhile, the random rough interface layer with the randomly distributed concave-convex patterns is prepared by adopting photoetching and etching modes, and the thickness of the interface layer can be accurately controlled within 2 microns, so that the thickness of the semiconductor material can be reduced, and the material cost is reduced.
The principles and methods of the present invention are further illustrated by the following examples of specific photoelectric conversion devices. Fig. 7 shows a schematic structure of a light emitting diode as a specific example of the photoelectric conversion device. As shown in fig. 7, the light emitting diode 20 includes a PN junction layer 210, a reflective layer 220, and a random rough interface layer 230 between the PN junction layer 210 and the reflective layer 220. The PN junction layer 210 sequentially includes, in a direction away from the reflective layer 220: a first conductive layer 221, a first current confinement layer 222, a light emitting functional layer 223, a second current confinement layer 224, a second conductive layer 225, wherein the random rough interface layer 230 is provided between the first conductive layer 221 and the reflective layer 220 on the side of the PN junction layer 210 close to the reflective layer 220. In addition, the light emitting diode 20 may further include a mechanical support layer 240, an electrode layer (not shown), and other film layers according to actual needs.
According to the embodiment of fig. 7, the random rough interface layer 230 is formed on the first conductive layer 221. Alternatively, an additional functional layer may be disposed between the first conductive layer 221 and the reflective layer 220, and the random rough interface layer 230 may be formed on the additional functional layer between the first conductive layer 221 and the reflective layer 220.
The light emitting diode 20 of the above-described structure is manufactured as follows.
First, as shown in fig. 8, taking an LED with an emission wavelength of 620nm as an example, a device structure having a light-emitting function is prepared on a substrate 400 by chemical vapor deposition epitaxy or physical deposition epitaxy, and the device structure includes, in order from the substrate side, a separation layer 401, a second conductive layer 225, a second current confinement layer 224, a light emission function layer 223, a first current confinement layer 222, and a first conductive layer 221. Substrate 400 may be a GaAs substrate, or other III-V, II-VI, or IV semiconductor substrate. The separation layer 401 may be GalnP, which is used as a barrier layer when etching the substrate, or may be made of materials having selective etching characteristics, such as AlAs, alGaAs, and AllnP, which are used in the substrate lift-off process. The first and second conductive layers are typically of a highly conductive material that is lattice matched to the substrate, such as a highly doped GaAs layer. The first current limiting layer and the second current limiting layer can respectively adopt materials with relatively high forbidden band widths, such as AllnP (Eg >2.4 eV), and mainly play a role in limiting the space positions of electrons and holes, so that the electrons and the holes can be recombined in the light-emitting function layer as much as possible to generate photons. The light emission function layer 223 may be made of a material system having a quantum well structure such as AlGalnP/GalnP.
Then, a photolithography mask having a random pattern distribution is prepared through a random function and a random process. The method comprises the following specific steps:
in the first step, two-dimensional random distribution coordinates are generated according to a computer random function. For the light wave with the wavelength of 620nm, the refractive index of a semiconductor is about 3.3, the effective wavelength in the semiconductor is 187nm, the 10-time effective wavelength is 1.87um, the single-point exposure area is 2um multiplied by 2um, the basic unit area of a chip is 500um multiplied by 500um, the exposure factor is 50%, the number of exposure points in the X direction and the Y direction is 176, and 30976 (176 multiplied by 176) two-dimensional random coordinates are required to be generated in total by adopting a computer uniform distribution random algorithm.
Alternatively, local randomization may be used to divide a 500um × 500um area into 25 100um × 100um areas, and then the method shown in fig. 6 is used, for a light wave with a wavelength of 620nm, the semiconductor refractive index is about 3.3, the effective wavelength in the semiconductor is 187nm, the 10-fold effective wavelength is 1.87um, the single-point exposure area is 2um × 2um, the basic unit area is 100um × 100um, the exposure factor is 50%, the number of exposure points in the X direction and the Y direction is 35, and 1225 (35 × 35) two-dimensional random coordinates are generated by using a computer uniform distribution random algorithm.
And secondly, preparing a two-dimensional random distribution pattern on the photoetching mask substrate by using a photoetching mask platemaking machine to obtain the photoetching mask plate with the two-dimensional random distribution pattern.
Then, a two-dimensional random pattern is prepared on the first conductive layer 221 by using the random mask plate, a photolithography process, an exposure machine with a wavelength of not more than 0.45um, and a suitable photoresist through spin coating, exposure, and development.
Next, grooves are etched on the first conductive layer 221 according to a two-dimensional random pattern by dry or wet etching, thereby forming a three-dimensional random concave-convex structure, i.e., a random rough interface layer 230, on the first conductive layer 221. An enlarged cross-sectional view of random rough interface layer 230 is shown in fig. 9.
Here, the etching may be dry or wet etching, and the etching depth is 1 to 2d, about 2um, where d =10 × lenda/n, where lenda is the wavelength of light in vacuum, and n is the refractive index of the semiconductor at that wavelength.
Further, it is preferable that the side walls of the grooves in the three-dimensional randomly distributed concave-convex pattern are formed at an angle of about 45 degrees to 135 degrees, preferably 60 degrees, with respect to the bottom surface. Specifically, the dry etching control realizes that the included angle between the side surface and the bottom surface of the groove deviates from a right angle, generally about 60 degrees, by changing the solution ratio and the temperature.
Then, the reflective layer 220 is formed by evaporating a highly reflective metal such as Al, ag, au, or an optical reflective structure such as a Distributed Bragg Reflector (Distributed Bragg Reflector). An oxide or sulfide having high transmittance may be interposed between the plurality of reflective layers to further improve the reflectance.
A metal support layer 240 may then be subsequently evaporated on the reflective layer 220 so that the substrate 400 may be subsequently removed.
After that, the separation layer 401 is etched or peeled by an etching process or a peeling process, the substrate 400 is removed from the device, and the second conductive layer 225 is exposed to form a device structure as shown in fig. 7, in which the a side is the air interface side. Photons generated when a voltage is applied to the light emitting function layer 223 of the PN junction layer 210 are emitted through the second conductive layer 225.
Fig. 10 shows a light path diagram in a light emitting diode. As shown in fig. 10, light emitted from the light emitting functional layer 223 at random angles is reflected by the reflective layer 220, and since the random rough interface layer 230 is formed between the reflective layer 220 and the PN junction layer 210, light emitted from the light emitting functional layer 223 at any angle toward the random rough interface layer 230 can be randomly reflected; meanwhile, light entering the inside of the device at the interface between the second conductive layer 225 and the air at the air interface side a due to total reflection also enters the air from the conductive layer in a direction smaller than the total reflection angle after undergoing one or more reflections at the random rough interface layer 230. Thus, according to the light emitting diode of the present embodiment, the light extraction efficiency can be improved, thereby greatly improving the electro-optic conversion efficiency of the light emitting diode.
Fig. 11 shows a schematic configuration diagram of a solar photovoltaic cell 30 as another specific example of the photoelectric conversion device. As shown in fig. 12, the solar photovoltaic cell 30 includes a PN junction layer 310, a reflective layer 320, and a random rough interface layer 330 between the PN junction layer 310 and the reflective layer 320. The PN junction layer 310 sequentially includes, in a direction away from the reflective layer 320: a first conductive layer 321, a first current confinement layer 322, a light absorption functional layer 323, a second current confinement layer 324, and a second conductive layer 325, wherein the random rough interface layer 330 is disposed between the first conductive layer 321 and the reflective layer 320 of the PN junction layer 310. In the figure, A is the air interface side. In addition, according to actual needs, the solar photovoltaic cell 30 may further include a transparent layer 340, and electrode layers 350 and 360 (see fig. 12) on the front and back surfaces. The process of manufacturing the solar photovoltaic cell 30 with the above structure is similar to the process of manufacturing the light emitting diode, and is not described herein again.
According to the embodiment of fig. 12, the random rough interfacial layer 330 is formed on the first conductive layer 321. Optionally, an additional functional layer may be disposed between the first conductive layer 321 and the reflective layer 320, and the random rough interface layer 330 may be formed on the additional functional layer between the first conductive layer 321 and the reflective layer 320.
Fig. 12 shows a schematic diagram of the light path in the solar photovoltaic cell 30. As shown in fig. 12, in the solar photovoltaic cell 30, external light P0 enters the PN junction layer (light absorbing layer) 310, and if only the plane reflection layer 320 is present, the light leaves the PN junction layer 310 in the P1 direction; path l of the whole light beam in the light-absorbing layer 1 =2d (d is the thickness of the light absorbing layer); due to the presence of the randomly rough interface layer 330, the path traveled by the light rays along the paths P2, P3 in the light absorbing layer:
l＝d+d/cosθ 1 +d/cosθ 1 +d/cosθ 2 +d/cosθ 2 ……,
the greater the number of reflections, the longer the path traveled, where θ 1 、θ 2 The angles between the first and second reflected light rays from the rough interface layer 330 and the normal to the flat surface, respectively. Provided that the angle is greater than the maximum angle of refraction theta from the light-absorbing layer to the light-transmitting layer c Wherein theta c ＝sin -1 (n 1/n 2), the light will propagate through the absorbing layer until it is completely absorbed by the absorbing layer. The absorption capacity of the absorption layer for photons is positively correlated with the path length traveled by the photons in the absorption layer.
As shown in FIG. 12, under the effect of the random rough interface layer 330, the optical path length l is d + d/cos θ after undergoing one reflection 1 Greater than 2d; after undergoing secondary reflection, is d + d/cos theta 1 +d/cosθ 1 Greater than 3d; after three reflections is d + d/cos θ 1 +d/cosθ 1 +d/cosθ 2 And is greater than 4d. In the gallium arsenide solar cell, the optical path of an absorption layer reaching 99% absorption is about 4 microns, a plane mirror is adopted, and the thickness needs 2 microns; if a random reflective interface is used, the thickness can be reduced to below 1 um.
The principles of the present invention have been illustrated above using light emitting diodes and photovoltaic cells as examples. It will be understood by those skilled in the art that the inventive concept can also be applied to photoelectric conversion devices such as photodetectors and lasers, which are not described in detail herein.
According to the embodiment of the invention, the reflection layer and the random rough interface layer are prepared on the lower surface of the photoelectric conversion device by adopting the technical means of photoetching, etching and coating, the random distribution of reflection angles is realized by utilizing a physical random process of superposition of a mathematical random function algorithm and quantum optics, the effective reflection of photons in the photoelectric conversion device is realized to the greatest extent, and the photoelectric or electro-optical conversion efficiency of the photoelectric conversion device is greatly improved; meanwhile, the photoetching and etching modes are adopted, so that the thickness of the rough interface layer can be accurately controlled within 2 microns, the thickness of the semiconductor material is reduced, and the material cost is reduced.
The foregoing embodiments are merely illustrative of the principles and configurations of this invention and are not to be construed as limiting thereof, since it will be apparent to those skilled in the art that many changes and modifications may be made without departing from the general inventive concept thereof. The protection scope of the present invention shall be subject to the scope defined by the claims of the present application.
Claims (14)
1. A photoelectric conversion device comprising:
a PN junction layer;
a reflective layer, which is disposed on the substrate,
the random rough interface layer is arranged between the PN junction layer and the reflecting layer and is provided with a randomly distributed concave-convex pattern generated by a random function of a computer.
2. The photoelectric conversion device according to claim 1, wherein the random rough interface layer is formed on a PN junction layer.
3. The photoelectric conversion device according to claim 1, wherein an additional functional layer is provided between the PN junction layer and the reflective layer, and a random rough interface layer is formed on the additional functional layer.
4. The photoelectric conversion device according to claim 1, wherein the photoelectric conversion device is a device for converting electric energy into optical energy, and the PN junction layer sequentially comprises, in a direction away from the reflective layer:
a first conductive layer;
a first current confinement layer;
a light emission functional layer;
a second current confinement layer;
a second conductive layer;
wherein the random rough interfacial layer is disposed between the first conductive layer and the reflective layer.
5. The photoelectric conversion device according to claim 4, wherein the random rough interface layer is formed on the first conductive layer.
6. The photoelectric conversion device according to claim 1, wherein the photoelectric conversion device is a device for converting light energy into electric energy, and the PN junction layer sequentially comprises, in a direction away from the reflective layer:
a first conductive layer;
a first current confinement layer;
a light absorbing functional layer;
a second current confinement layer;
a second conductive layer;
wherein the random rough interfacial layer is disposed between the first conductive layer and the reflective layer.
7. The photoelectric conversion device according to claim 6, wherein the random rough interface layer is formed on the first conductive layer.
8. A method of manufacturing a photoelectric conversion device, comprising:
preparing a PN junction layer;
preparing a random rough interface layer on the backlight side of the PN junction layer, wherein the random rough interface layer is provided with a randomly distributed concave-convex pattern generated by a random function of a computer; and
and forming a reflecting layer on the random rough interface layer.
9. The manufacturing method of a photoelectric conversion device according to claim 8, wherein preparing a random rough interface layer on a backlight side of the PN junction layer comprises:
generating a two-dimensional random distribution coordinate by using a computer random function;
preparing a photoetching mask plate according to two-dimensional random distribution coordinates generated by a computer random function; and
and preparing a random rough interface layer on the backlight side of the PN junction layer by using a photoetching mask.
10. The method for manufacturing a photoelectric conversion device according to claim 9, wherein the preparing a random rough interface layer on a backlight side of the PN junction layer using a photolithography mask comprises:
forming a two-dimensional random distribution pattern on the backlight side of the PN junction layer by photoetching by using the photoetching mask; and
and etching the two-dimensional randomly distributed pattern to form a three-dimensional randomly distributed concave-convex pattern.
11. The method for manufacturing a photoelectric conversion device according to claim 10, wherein a depth of the groove in the formed three-dimensional randomly distributed concave-convex pattern is 1d to 2d, where d =10 × lenda/n, where lenda is a wavelength of light in a vacuum, and n is a refractive index of a semiconductor at the wavelength.
12. The method of manufacturing a photoelectric conversion device according to claim 9, wherein the generating two-dimensional randomly distributed coordinates using a computer random function includes:
determining the exposure area d of each exposure spot 2 D =10 × lenda/n; where lena is the wavelength of light in vacuum and n is the refractive index of the semiconductor at that wavelength;
the number a x b of random numbers to be generated on each chip unit is calculated, wherein,
a is the number of random points required to be generated in the X direction, b is the number of random points required to be generated in the Y direction, s is an exposure factor, namely the ratio of the exposure area to the total area, X is the width of one chip unit, and Y is the length of one chip unit;
and generating exposure coordinates (x, y) of the lithography mask by utilizing a computer random function according to the number a multiplied by b of the random numbers, wherein the 0-type and x-type and the 0-type and y-type are respectively formed by the layers.
13. The method of manufacturing a photoelectric conversion device according to claim 9, wherein the generating two-dimensional randomly distributed coordinates using a computer random function includes:
dividing the chip basic unit into m X n chip regions, each region having a width of X/m and a length of Y/n,
determining the exposure area d of each exposure spot 2 D =10 × lenda/n; where lenda is the wavelength of light in vacuum and n is the refractive index of the semiconductor at that wavelength;
the number a1 × b1 of random numbers to be generated on each chip area is calculated, wherein,
a1 is the number of random points to be generated in the X direction, b1 is the number of random points to be generated in the Y direction, and s is the exposure factor, i.e. exposureThe ratio of the area to the total area, X is the width of one chip unit, and Y is the length of one chip unit;
and generating exposure coordinates (x, y) of the lithography mask by utilizing a computer random function according to the number a1 × b1 of the random numbers, wherein the 0-yarn x-yarn X/m and the 0-yarn y-yarn Y/n are formed.
14. The method of manufacturing a photoelectric conversion device according to claim 13,
or
Wherein the sigma is the preparation precision of the photoetching mask.
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| US4589972A (en) * | 1984-07-30 | 1986-05-20 | Martin Marietta Corporation | Optically black coating with improved infrared absorption and process of formation |
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