阅读说明：本技术 一种可产生热载流子弛豫效应的低维硅设计制备方法 (Low-dimensional silicon design preparation method capable of generating hot carrier relaxation effect ) 是由 严文生 臧月 于 2021-07-12 设计创作，主要内容包括：本发明公开了一种可产生热载流子弛豫效应的低维硅设计制备方法,包括S10,声子能带设计；S20,设计具有人工声子带隙的低维硅结构；S30,制备结构化的低维硅；S40,结构表征与功能化测量。本发明根据设计的具有人工声子带隙结构的低维硅结构,采用本发明的制备方法,可以实现结构规整、均一性好、高重复性的二维周期性硅结构。(The invention discloses a low-dimensional silicon design preparation method capable of generating hot carrier relaxation effect, which comprises S10, designing a phonon energy band; s20, designing a low-dimensional silicon structure with an artificial phonon band gap; s30, preparing structured low-dimensional silicon; and S40, structural characterization and functional measurement. According to the designed low-dimensional silicon structure with the artificial phonon band gap structure, the preparation method can realize the two-dimensional periodic silicon structure with regular structure, good uniformity and high repeatability.)

1. A method for preparing a low-dimensional silicon design capable of generating a hot carrier relaxation effect is characterized by comprising the following steps:

s10, designing a phonon energy band;

s20, designing a low-dimensional silicon structure with an artificial phonon band gap;

s30, preparing structured low-dimensional silicon;

and S40, structural characterization and functional measurement.

2. The method as claimed in claim 1, wherein the step of S10, phonon band design, comprises the steps of:

s11, selecting an original sample as an ultra-thin monocrystalline silicon film with the thickness of 400-600nm extending on an aluminum oxide substrate;

s12, modeling and calculating the simulation: a simulation was constructed to have holes in a two-dimensional structure and arranged in a square, where there were 3 variables, respectively, the thickness d of the film, the radius r of the holes, and the hole period length P, where d >0, r >0, and P >2 r.

3. The method for manufacturing a low-dimensional silicon design capable of generating hot carrier relaxation effect as claimed in claim 2, wherein said step S20 of designing a low-dimensional silicon structure with artificial phonon band gap comprises the following steps:

s21, in the aspect of material mechanical properties, the material of the film is set to be crystalline silicon, the holes are air, and in the calculation, elastic constants of the crystalline silicon and the air are respectively adopted to represent the two materials;

s22, when calculating the band gap of the phononic crystal, adopting a generalized elastic wave equation containing time variables, and because the structure has periodic symmetry, only one minimum unit cell needs to be calculated during calculation, and a periodic boundary condition of the Bloch is added;

s23, carrying out simulation calculation on the sample to enable the sample to present a phonon forbidden band;

s24, obtaining the parameters from the simulation calculation as: and r is 530nm and P is 1100 nm.

4. The method for manufacturing a low dimensional silicon design capable of generating hot carrier relaxation effect as claimed in claim 3, wherein said step of S30, manufacturing a structured low dimensional silicon, comprises the steps of:

s31, performing ultrasonic cleaning on the original sample by ethanol, acetone and deionized water respectively, adsorbing and fixing the sample on a gel homogenizing instrument, spin-coating a layer of liquid PMMA on the sample, heating the substrate at the temperature of 200-;

s32, sending the sample into an electron beam exposure device, directly drawing on the substrate coated with the photosensitive resist by using an electron beam, and scanning the low-dimensional silicon structure designed in S20 on the surface of the sample by using the electron beam;

s33, sending the sample into a reactive ion etching cavity for etching treatment, wherein the reaction gas is SF₆And O₂，SF₆The flow rate is 50-70sccm and O₂The flow is 40-55sccm, the pressure in the cavity is 30-50mTorr, the radio frequency power range is 80-120W, and the etching time is 7-12s, so that the silicon in the circular area is removed, and a two-dimensional silicon structure consisting of the hole array is formed.

5. The method as claimed in claim 4, wherein the time of ultrasonic cleaning in S31 is 5-20 min.

6. The method as claimed in claim 4, wherein the electron beam exposure in S32 is performed in a scanning exposure mode.

7. The method for manufacturing a low dimensional silicon design capable of generating hot carrier relaxation effect as claimed in claim 1, wherein said S40, structural characterization and functional measurement, comprises the following steps:

s41, performing scanning electron microscope characterization on the sample obtained in the S30;

and S42, measuring the characteristics of the hot carrier relaxation effect by adopting ultra-fast transient absorption.

Technical Field

The invention belongs to the technical field of material preparation, and relates to a low-dimensional silicon design preparation method capable of generating a hot carrier relaxation effect.

Background

In general, hot carriers refer to those with an initial kinetic energy at least in the conduction (or valence) band k_BElectrons (or holes) in the boltzmann distribution above T. They are the subsequent thermalization of the non-equilibrium carriers generated after excitation by external light. These hot carriers eventually reach equilibrium with the semiconductor lattice through carrier cooling processes such as carrier-phonon scattering, auger processes, etc. Hot carrier relaxation refers to delaying the hot carrier cooling time. By utilizing the principle of hot carrier relaxation effect, the method has important application prospect and value in the fields of high-efficiency solar cells, photodetectors, field effect transistor integrated circuits and the like.

To date, hot carrier relaxation effects have been found in many materials and structures, such as graphene thin films, III-V semiconductor quantum wells or nanowires, carbon nanotubes, transition metal chalcogenides, black phosphorus, perovskite thin films, silicon quantum dots, and the like. In contrast to these previous reports, the materials and structures of interest in the present invention are novel artificially structured low-dimensional silicon thin films. The advantages are two: firstly, the silicon material has the advantages of no toxicity, rich earth crust reserves, stable device performance and the like. Silicon is currently the most used and mature semiconductor material for integrated circuit and optoelectronic device applications. Secondly, compared with the silicon quantum dots, the silicon film and the artificial structurization have the advantages of high controllability, structural repeatability, uniformity and the like in preparation, so that the performances of devices in different batches can be kept highly stable and consistent.

Disclosure of Invention

Based on the above purpose, the invention provides a low-dimensional silicon design preparation method capable of generating hot carrier relaxation effect, comprising the following steps:

s10, designing a phonon energy band;

s20, designing a low-dimensional silicon structure with an artificial phonon band gap;

s30, preparing structured low-dimensional silicon;

and S40, structural characterization and functional measurement.

Preferably, the S10, phonon band designing, includes the following steps:

s11, selecting an original sample as an ultra-thin monocrystalline silicon film with the thickness of 400-600nm extending on an aluminum oxide substrate;

s12, modeling and calculating the simulation: a simulation was constructed to have holes in a two-dimensional structure and arranged in a square, where there were 3 variables, respectively, the thickness d of the film, the radius r of the holes, and the hole period length P, where d >0, r >0, and P >2 r.

Preferably, the S20, designing the low-dimensional silicon structure with artificial phonon bandgap, includes the following steps:

s21, in the aspect of material mechanical properties, the material of the film is set to be crystalline silicon, the holes are air, and in the calculation, elastic constants of the crystalline silicon and the air are respectively adopted to represent the two materials;

s22, when calculating the band gap of the phononic crystal, adopting a generalized elastic wave equation containing time variables, and because the structure has periodic symmetry, only one minimum unit cell needs to be calculated during calculation, and a periodic boundary condition of the Bloch is added;

s23, carrying out simulation calculation on the sample to enable the sample to present a phonon forbidden band;

s24, obtaining the parameters from the simulation calculation as: and r is 530nm and P is 1100 nm.

Preferably, the S30, preparing the structured low dimensional silicon, comprises the following steps:

s31, performing ultrasonic cleaning on the original sample by ethanol, acetone and deionized water respectively, adsorbing and fixing the sample on a gel homogenizing instrument, spin-coating a layer of liquid PMMA on the sample, heating the substrate at the temperature of 200-;

s32, sending the sample into an electron beam exposure device, directly drawing on the substrate coated with the photosensitive resist by using an electron beam, and scanning the low-dimensional silicon structure designed in S20 on the surface of the sample by using the electron beam;

s33, sending the sample into a reactive ion etching cavity for etching treatment, wherein the reaction gas is SF₆And O₂，SF₆The flow rate is 50-70sccm and O₂The flow is 40-55sccm, the pressure in the cavity is 30-50mTorr, the radio frequency power range is 80-120W, and the etching time is 7-12s, so that the silicon in the circular area is removed, and a two-dimensional silicon structure consisting of the hole array is formed.

Preferably, the ultrasonic cleaning time in S31 is 5-20 min.

Preferably, the electron beam exposure in S32 adopts a scanning exposure mode.

Preferably, the S40, the structural characterization and the functional measurement, includes the following steps:

s41, performing scanning electron microscope characterization on the sample obtained in the S30;

and S42, measuring the characteristics of the hot carrier relaxation effect by adopting ultra-fast transient absorption.

The beneficial effects of the invention at least comprise:

1. according to the measurement of the relaxation property of the hot carrier of the two-dimensional silicon structure, the method has the obvious effect of inhibiting the recombination of the hot carrier; the hot carrier lifetime increases significantly from 2-3 picoseconds to more than 20 picoseconds;

2. based on the principle of inhibiting thermalization of hot carriers, the two-dimensional silicon structure prepared by the invention can be used for developing devices such as ultra-high conversion efficiency solar cells, photodetectors, field effect transistor integrated circuits and the like;

3. the novel structure hot carrier relaxation effect is realized by the preparation method of the two-dimensional periodic silicon structure with regular structure, good uniformity and high repeatability.

Drawings

FIG. 1 is a flowchart illustrating steps in a method for manufacturing a low dimensional silicon design that produces hot carrier relaxation effects in accordance with an embodiment of the present invention;

FIG. 2 is a schematic diagram of a two-dimensional silicon with artificial phonon bandgap of S20 design of a method for manufacturing a low-dimensional silicon design capable of generating hot carrier relaxation effect according to an embodiment of the present invention;

FIG. 3 is a two-dimensional silicon band diagram with artificial phonon bandgap design S20 of a low-dimensional silicon design fabrication process to produce hot carrier relaxation effects in accordance with an embodiment of the present invention;

FIG. 4 is a scanning electron microscope image of a two-dimensional structured silicon film prepared by the method for preparing a low-dimensional silicon design capable of generating hot carrier relaxation effect according to an embodiment of the present invention;

fig. 5 is a graph comparing the ultrafast transient absorption spectrum of the two-dimensional structured silicon thin film prepared by the method for preparing the low-dimensional silicon design capable of generating hot carrier relaxation effect according to the embodiment of the present invention with the reference sample of the prior art.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

On the contrary, the invention is intended to cover alternatives, modifications, equivalents and alternatives which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of the present invention, certain specific details are set forth in order to provide a better understanding of the present invention. It will be apparent to one skilled in the art that the present invention may be practiced without these specific details.

Referring to fig. 1, the method comprises the following steps:

s10, designing a phonon energy band;

s20, designing a low-dimensional silicon structure with an artificial phonon band gap;

s30, preparing structured low-dimensional silicon;

and S40, structural characterization and functional measurement.

S10, designing a phonon energy band, comprising the following steps:

s11, selecting an original sample as an ultra-thin monocrystalline silicon film with the thickness of 400-600nm extending on an aluminum oxide substrate;

s12, modeling and calculating the simulation: the simulation was constructed to have holes in a two-dimensional structure and arranged in squares, see fig. 2, where there are 3 variables, respectively, the thickness d of the film, the radius r of the holes, and the period length P of the holes, where d >0, r >0, and P >2 r.

S20, designing a low-dimensional silicon structure with an artificial phononic bandgap, comprising the following steps:

s21, in the aspect of material mechanical properties, the material of the film is set to be crystalline silicon, the holes are air, and in the calculation, elastic constants of the crystalline silicon and the air are respectively adopted to represent the two materials;

s22, when calculating the band gap of the phononic crystal, adopting a generalized elastic wave equation containing time variables, and because the structure has periodic symmetry, only one minimum unit cell needs to be calculated during calculation, and a periodic boundary condition of the Bloch is added;

s23, carrying out simulation calculation on the sample to enable the sample to present a phonon forbidden band; referring to fig. 3, dotted dashed lines indicate the frequency band structure of the phonon crystal, and the middle solid region indicates a phonon forbidden band.

S24, obtaining the parameters from the simulation calculation as: r 530nm, P1100 nm, d 500-600 nm.

S30, preparing the structured low-dimensional silicon, which comprises the following steps:

s31, performing ultrasonic cleaning on the original sample by ethanol, acetone and deionized water respectively, wherein the ultrasonic cleaning time is 5-20 min; adsorbing and fixing the sample on a gel homogenizing instrument, spin-coating a layer of liquid PMMA (polymethyl methacrylate) on the sample, heating the substrate at the temperature of 200-;

s32, sending the sample into electron beam Exposure (EBL) equipment, directly drawing on the substrate coated with the photosensitive resist by using an electron beam, and scanning the low-dimensional silicon structure designed in S20, namely the graph structure of FIG. 2 on the surface of the sample by using a scanning exposure mode;

s33, sending the sample into a reactive ion etching chamber (RIE) for etching treatment, wherein the reaction gas is SF₆And O₂，SF₆The flow rate is 50-70sccm and O₂The flow is 40-55sccm, the pressure in the cavity is 30-50mTorr, the radio frequency power range is 80-120W, and the etching time is 7-12s, so that the silicon in the circular area is removed, and a two-dimensional silicon structure consisting of the hole array is formed.

S40, structural characterization and functional measurement, including the following steps:

s41, performing scanning electron microscope characterization on the sample obtained in the S30; the actual electron micrograph obtained is shown in FIG. 4.

S42, measuring the hot carrier relaxation effect characteristic by adopting ultrafast transient absorption, wherein the measuring result is shown in figure 5, and the hot carrier service life can be estimated by fitting, so that the reference sample (namely, the original crystalline silicon film in the prior art) and the two-dimensional silicon structure prepared by the invention present obviously different curve characteristics, wherein the hot carrier service life of the reference sample is 2-3 picoseconds, and the hot carrier service life of the two-dimensional silicon structure of the invention is higher than 20 picoseconds. This indicates that the two-dimensional silicon structure of the present invention exhibits a significant hot carrier relaxation effect, which can be used to extend the cooling time of hot carriers. The effect can be used for developing devices such as ultra-high conversion efficiency solar cells, photodetectors, field effect transistor integrated circuits and the like.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.