《多晶硅生产技术》课程项目化教学改革实践

随着信息化、数字化技术的发展,学生获取知识的渠道增多,传统的教学方法已不适应现代社会的发展,进行课程教学改革势在必行。从多晶硅生产技术项目化课程设计、实践教学、课程考核、教学形式和方法入手,提出解决这些问题的具体意见和建议。自《多晶硅生产技术》实施课程项目化教学改革以来,学生综合素养、自主学习能力普遍比未实施课改的学生强。     

多晶硅电炉用10000kVA干式还原炉变压器的设计

介绍了10000kVA干式还原炉变压器电磁设计的过程及其结构设计,并通过模拟仿真及产品样机试验进行了验证。     

多晶硅还原炉低电压启动转高电压启动设备结构改造

目前国内多晶硅生产中,还原炉多采用高电压击穿的方式启动,但国外多晶硅生产中多采用低电压击穿,一些进口还原炉采用了低电压启动的结构设计。现本文将以MSA还原炉为例,分析阐述满足低压启动还原炉改成高压启动条件,对炉体结构的改造方案。     

多晶硅副产物四氯化硅的利用

随着绿色能源太阳能的大规模开发利用,光伏电池原料多晶硅的用途越来越广泛.生产多晶硅的方法以西门子法用的最广,在生产多晶硅原料三氯氢硅的过程中会产生大量的副产物四氯化硅,其对环境的污染相当严重,如何处理这些副产物,这个问题亟待解决.介绍了多种四氯化硅的再利用方法,如可以用来制造气相白炭黑,合成有机硅产品,制备高纯光纤,用...     

Fabrication of high breakdown voltage silicon Schottky barrier diodes using various edge termination structures

In this work, the design and fabrication of Au/n-Si Schottky barrier diodes (SBDs) with various edge termination schemes, including a reduced-surface-field-type lateral super-junction, a polycrystalline silicon (poly-Si) floating ring, and a p⁺-poly-Si guard ring, are presented. Experimental results show that the reverse leakage current of the proposed SBDs was reduced and the breakdown voltage increased with an increase of the poly-Si width of the guard ring.It was found that the device and fabrication technology developed in the present study is applicable to the realization of SBDs with a high breakdown voltage (≥ 160 V), a low reverse current density (≤ 5.6 μA/cm²), a low forward voltage drop (≤ 5.6 V @ 1 A/cm²), and an adjustable Schottky barrier height of 0.764 to 0.784 eV.     

Radiative energy loss in a polysilicon CVD reactor

This work aims at understanding the energy loss in the polysilicon deposition reactor during the production of solar grade silicon. The radiative heat transfer between the polysilicon rods and the reactor wall in the so-called Siemens reactor is studied in detail in this paper. First, the most commonly used reactor configuration, 36 rods in three rings, is explained, detailing the particular radiation transfer of each rod toward the wall. Based on this analysis, some proposals for diminishing the energy loss are proposed: enlarge the reactor capacity, improve the properties of the reactor wall and introduce thermal shields. The impact of each proposal on the energy savings is quantified. If the reactor capacity is enlarged from 36 to 60 rods, the energy savings would be around 11 kWh per kg of polysilicon produced (kWh kg⁻¹). Increasing the reflectivity of the wall, the savings would be around 17 kWh kg⁻¹. And finally, the potential for cost reduction because of the introduction of thermal shields would be 20 kWh kg⁻¹.     

Thermal dependence of low-frequency noise in polysilicon thin film transistors

Thermal dependence of low frequency noise in low temperature (≤ 600 °C) polysilicon thin film transistors is studied in devices biased from weak to moderate inversion and operating in the linear mode. Drain current noise spectral density, measured in the temperature range from 260 K to 310 K, is thermally activated following the Meyer Neldel rule. Analysis of the thermal activation of noise, supported by the theory of trapping/detrapping processes of carriers into oxide traps located close to the interface, leads to the calculation of the deep state interface distribution in function of the Meyer Neldel characteristic energy.     

Manufacture of Granular Polysilicon from Trichlorosilane in a Fluidized‐Bed Reactor

Manufacturing of polysilicon by chemical vapor deposition from SiHCl₃ in a fluidized‐bed reactor was studied. The effects of reaction temperature, H₂/SiHCl₃ ratio, gas velocity, and seed particle loading were evaluated. The outlet gas composition was analyzed by gas chromatography. The physical features of the product particles were determined by scanning electron microscopy and laser particle size analyzer. Well‐grown product particles were obtained. The temperature and H₂/SiHCl₃ ratio significantly affected conversion, yield, and selectivity, which were less affected by gas velocity and seed particle loading at higher temperatures. The surface reaction kinetics determined the product yield only at lower temperatures, and thermodynamic equilibrium was approached at temperatures above 900 °C.     

用深能级瞬态谱方法研究多晶硅薄膜的晶粒界面态

本文发展了一个改进的深能级瞬态谱方法——C~2DLTS方法,并将该方法应用于硅离于注入再结晶法处理的多晶硅薄膜的晶粒界面态的研究。实验结果表明:多晶硅薄膜的晶粒界面态和硅离子注入后多晶硅薄膜的晶粒组成结构是密切相关的。     

Simple analytical solution and efficiency improvement of polysilicon emitter solar cells

A simple analytical model has been developed to simulate the performance of solar cells with polysilicon contact on the front surface. The polysilicon layer with a columnar grain structure is modeled by an effective recombination velocity using a two-dimensional transport equation. A one-dimensional transport equation in the single-crystal emitter is solved, taking into account bulk recombination and non-uniformly doped emitter. Then, simple analytical expressions for the emitter reverse saturation current and light-generated current densities are obtained. The collection of the light-generated carriers in polysilicon layer has been discussed and an analytical solution of the light-generated current is derived. The results show that the polysilicon layer can result in a decrease in emitter reverse saturation current density and an increase in solar cell photovoltaic parameters. In fact, the emitter region should not be treated as a ‘dead layer’ because thin polysilicon layer front surface contact gives an improvement of about 60 mV for the open-circuit voltage, 3.6 mA/cm² for the photocurrent, and 3.9% for the cell efficiency.