CN-122028544-A - Three-dimensional bird nest structure c-Si@a-Si core/shell nanowire and preparation method thereof

CN122028544ACN 122028544 ACN122028544 ACN 122028544ACN-122028544-A

Abstract

The application discloses a three-dimensional bird nest structure c-Si@a-Si core/shell nanowire and a preparation method thereof, and relates to the technical field of performance test of optoelectronic devices, the method comprises the following steps of S1, utilizing low-melting point metal to induce and grow p-type doped crystalline silicon nanowire in a low-pressure chemical vapor deposition system, utilizing an excimer laser to combine a phase-shifting grating mask technology, accurately regulating and controlling energy distribution of laser, accurately regulating and controlling light energy, enabling photoelectric response and light trapping enhancement characteristics of the silicon-based solid-state core/shell nanowire to be accurately evaluated when light absorption characteristics and fluorescence quantum efficiency of the silicon-based solid-state core/shell nanowire are measured, and in addition, introducing microstructures into the nanowire through designing a periodical crystallization area, wherein the microstructures promote light to undergo multiple reflection and refraction in the material, and the enhanced light path not only optimizes primary absorption efficiency of light, but also provides secondary absorption opportunities for light which is not absorbed for the first time.

Inventors

ZHANG PENGZHAN
LIU XINYU
HE JIAMING
WANG DANBEI
ZHANG LENG
WU KONGPING
CHEN KUNJI

Assignees

金陵科技学院

Dates

Publication Date: 20260512
Application Date: 20260128

Claims (10)

1. The three-dimensional bird nest structure c-Si@a-Si core/shell nanowire is characterized in that a c-Si nanowire array is grown on a glass substrate by a chemical vapor deposition method, a layer of a-Si intrinsic absorption layer is covered outside the c-Si nanowire, the c-Si nanowire is doped into a p-type semiconductor, the a-Si intrinsic absorption layer is doped into an n-type semiconductor, a part of a region of the a-Si intrinsic absorption layer is converted into a periodic crystallization region after laser crystallization treatment, and the intrinsic absorption layer consists of the periodic crystallization region and an amorphization region.
2. A method for preparing the three-dimensional bird nest structure c-si@a-Si core/shell nanowire according to claim 1, comprising the following steps: Step S1, using low-melting point metal to induce and grow p-type doped c-Si nanowires on a glass substrate in a low-pressure chemical vapor deposition system; S2, covering an a-Si intrinsic absorption layer formed by a silicon-based amorphous solid film on the c-Si nanowire, and doping the a-Si intrinsic absorption layer into an n-type semiconductor; Step S3, laser crystallization technology is used for carrying out laser treatment of different energy on the a-Si intrinsic absorption layer, and a periodic crystallization area is formed in the a-Si intrinsic absorption layer so as to improve the anti-reflection and absorption enhanced optical properties of the intrinsic absorption layer to form a three-dimensional bird nest structure c-Si@a-Si core/shell nanowire; And S4, measuring and calculating the fluorescence external quantum efficiency and the fluorescence internal quantum efficiency of the three-dimensional bird nest structure c-Si@a-Si core/shell nanowire.
3. The method for preparing the three-dimensional bird nest structure c-Si@a-Si core/shell nanowire according to claim 2, wherein the specific steps for improving the anti-reflection and light trapping enhancement characteristics of the intrinsic absorption layer in the step S3 are as follows: Step S31, performing laser crystallization on the a-Si intrinsic absorption layer by using a KrF excimer pulse laser; s32, performing energy modulation on laser in the x and y directions by using a phase shift grating mask to generate two-dimensional energy distribution on the surface of the a-Si intrinsic absorption layer; step S33, the energy distribution formed after the laser passes through the phase-shifting grating mask has periodicity, wherein the period of the graduation of the phase-shifting grating mask is 2 mu m to 400 nm so as to modulate the light field distribution of the radiation to the surface of the a-Si intrinsic absorption layer; and step S34, under the condition that the crystallization threshold intensity is reached or exceeded, the a-Si intrinsic absorption layer is induced to be changed from an amorphous state to a liquid state by using laser, and a periodic crystallization area is formed through a liquid phase crystallization process.
4. The method of claim 3, wherein the characteristic parameters of the KrF excimer pulse laser in step S31 include a wavelength of 248 nm, a pulse width of 30 ns, a frequency of 10 Hz, an output power of 80 to 160 mJ/pulse, and a total energy loss of the laser from the light exit of the laser to the sample surface via the beam homogenizer and the mirror is less than 10%.
5. The method for preparing a three-dimensional bird' S nest structure c-si@a-Si core/shell nanowire according to claim 3, wherein in the step S34, the periodic crystallization area is formed by raising the surface of the a-Si film to form a microstructure due to the fact that the density of solid phase Si is lower than that of liquid phase Si in the crystallization process, the microstructure enables incident light to be refracted and reflected for multiple times inside the c-si@a-Si core/shell nanowire, the path of light in the absorption layer is increased, and unabsorbed light is returned to the absorption layer again for secondary absorption.
6. The method for preparing a three-dimensional bird 'S nest structure c-si@a-Si core/shell nanowire according to claim 2, wherein the method is characterized in that in step S4, when the fluorescence external quantum efficiency of the three-dimensional bird' S nest structure c-si@a-Si core/shell nanowire sample is measured and calculated, the light reflected and transmitted by the sample is collected by using an integrating sphere, so as to obtain the fluorescence external quantum efficiency of the sample.
7. The method for preparing the three-dimensional bird nest structure c-Si@a-Si core/shell nanowire according to claim 2, wherein the method is characterized in that in the step S4, when the fluorescence internal quantum efficiency of the bird nest structure c-Si@a-Si core/shell nanowire sample is measured and calculated, the temperature-variable fluorescence spectrum (TD-PL) is adopted to test the fluorescence internal quantum efficiency of the film, and the obtained optical parameters are measured according to an integrating sphere and the fluorescence internal quantum efficiency of the sample is obtained by combining a plane geometry optical principle with spherical integration.
8. The method for preparing the three-dimensional bird nest structure c-Si@a-Si core/shell nanowire according to claim 2, wherein in the step S4, an excimer laser is used for exciting a film sample, the excitation is performed under a variable temperature condition, photoluminescence decay curves at different temperatures are recorded, and the fluorescence internal quantum efficiency is calculated by analyzing temperature-dependent service life changes.
9. The method for preparing the three-dimensional bird nest structure c-Si@a-Si core/shell nanowire according to claim 2, wherein transmittance and absorptivity are obtained through optical measurement in the step S4, and the obtained transmittance and absorptivity are substituted into a beer-lambert law formula to obtain fluorescence internal quantum efficiency.
10. The method for preparing a three-dimensional bird' S nest structure c-si@a-Si core/shell nanowire according to claim 2, wherein 1D or 2D nc-Si arrays having a period of 2 μm are prepared on a glass substrate before the c-Si nanowire is grown in step S1, light energy is directly irradiated to the active areas of the crystallization ridges, thereby reducing the effective coverage area of the light entrance surface, and light reflection can be reduced due to the shape and arrangement of the 1D or 2D nc-Si arrays.

Description

Three-dimensional bird nest structure c-Si@a-Si core/shell nanowire and preparation method thereof Technical Field The invention belongs to the technical field of performance test of optoelectronic devices, and particularly relates to a three-dimensional bird nest structure c-Si@a-Si core/shell nanowire and a preparation method thereof. Background With the rapid development of optoelectronic technology, it is becoming increasingly important to accurately evaluate the performance of optoelectronic devices, such as LEDs and solar cells. Among these, light absorption characteristics are one of the core indicators for evaluating the performance of these devices. The conventional laser crystallization preparation methods have some limitations, and the methods often cannot accurately control the distribution of laser energy, and may cause uneven energy distribution on the surface of the film, thereby causing overheating or insufficient energy in local areas, and the uneven energy distribution may seriously affect the accuracy and repeatability of the measurement of the light absorption characteristics. Furthermore, if the core/shell nanowire structure is not specifically optimized, the light rays will be reflected rather than absorbed at the surface when entering the shell film. This phenomenon makes the actual absorption rate of the shell layer far lower than the theoretical expectation, resulting in inaccurate calculation of the light absorption coefficient based on the absorption rate. More seriously, many conventional fabrication methods lack efficient optical path management strategies and light trapping structures, resulting in inefficient propagation and scattering of light within the material. This not only reduces the effective use of light, but also further reduces the accuracy of the measurement of the overall light absorption coefficient. The present invention has been made in view of this. Disclosure of Invention The invention aims to overcome the defects of the prior art, and provides a three-dimensional bird nest structure c-Si@a-Si core/shell nanowire and a preparation method thereof, which solve the problems in the prior art. In order to solve the technical problems, the invention adopts the basic conception of the technical scheme that: The three-dimensional bird nest structure c-Si@a-Si core/shell nanowire is formed by growing a c-Si nanowire array on a glass substrate by a chemical vapor deposition method, a layer of a-Si intrinsic absorption layer is covered outside the c-Si nanowire, the c-Si nanowire is doped into a p-type semiconductor, the a-Si intrinsic absorption layer is doped into an n-type semiconductor, a partial region of the a-Si intrinsic absorption layer is converted into a periodic crystallization region after laser crystallization treatment, and the intrinsic absorption layer consists of the periodic crystallization region and an amorphization region. The preparation method of the three-dimensional bird nest structure c-Si@a-Si core/shell nanowire comprises the following steps: Step S1, using low-melting point metal to induce and grow p-type doped c-Si nanowires on a glass substrate in a low-pressure chemical vapor deposition system; S2, covering an a-Si intrinsic absorption layer formed by a silicon-based amorphous solid film on the c-Si nanowire, and doping the a-Si intrinsic absorption layer into an n-type semiconductor; Step S3, laser crystallization technology is used for carrying out laser treatment of different energy on the a-Si intrinsic absorption layer, and a periodic crystallization area is formed in the a-Si intrinsic absorption layer so as to improve the anti-reflection and absorption enhanced optical properties of the intrinsic absorption layer to form a three-dimensional bird nest structure c-Si@a-Si core/shell nanowire; And S4, measuring and calculating the fluorescence external quantum efficiency and the fluorescence internal quantum efficiency of the three-dimensional bird nest structure c-Si@a-Si core/shell nanowire. Optionally, the specific steps for improving the anti-reflection and light trapping enhancement properties of the intrinsic absorption layer in step S3 are as follows: Step S31, performing laser crystallization on the a-Si intrinsic absorption layer by using a KrF excimer pulse laser; s32, performing energy modulation on laser in the x and y directions by using a phase shift grating mask to generate two-dimensional energy distribution on the surface of the a-Si intrinsic absorption layer; step S33, the energy distribution formed after the laser passes through the phase-shifting grating mask has periodicity, wherein the period of the graduation of the phase-shifting grating mask is 2 mu m to 400 nm so as to modulate the light field distribution of the radiation to the surface of the a-Si intrinsic absorption layer; and step S34, under the condition that the crystallization threshold intensity is reached or exceeded, the a-Si intrinsic absorption