用于高效太阳电池的硅基微纳结构及制备

介绍了用于高效太阳电池的几种硅基微纳结构的最新研究进展,重点介绍了几种硅基微纳结构的制备方法,如阳极腐蚀制备多孔硅、各向异性制绒以及气液固(VLS)生长纳米线等,并对各种方法的特点作了分析比较,指出了各种方法存在的问题。最后对今后研究的方向做了展望,由于太阳电池在性能提高以及产业应用方面的需求,未来用于高效太阳电池的硅基微纳结构仍是研究的热点之一。进一步提升其对太阳电池效率的优化能力将是研究的重要关注点,而其制备技术也将向着低成本、大规模及可控制的方向发展。     

太阳能发电技术与应用 第三讲:最大功率点跟踪技术

3.1硅太阳电池的等效电路太阳电池一般由半导体材料制成,图1是常见的硅太阳电池在日照情况下的等效电路。图中Isc称之为光生电流,或短路电流,其值正比于太阳电池的面积和入射光的辐照度,而且它是在负载RL短路时,太阳电池可能输出的最大电流;ID为暗电流,是太阳电池在无光照情况下外加电压时,流过内部p-n结的单向电流。     

聚光太阳电池及其研究进展

介绍了聚光太阳电池的电特性和热特性;综述了聚光硅太阳电池的特点和研究进展,包括背结聚光硅电池、激光刻槽埋栅聚光硅电池和其他具有传统n+/p/p+结构的聚光硅电池;总结了聚光多结太阳电池的研究现状、效率的损失机理以及实现超高效电池的途径.从目前的研究进展可以看出,研发新结构、超高效的聚光太阳电池以降低光伏发电成本的前景一片光明.     

基于CMOS工艺的横向多晶硅p^＋p^-n^＋结红外微测辐射热计

基于多晶硅p-n结正向压降的温度特性,应用标准CMOS工艺,结合体硅微机械加工技术,研制成功非制冷红外微测辐射热计.本文详细分析了横向多晶硅p+p-n+结的温度特性,给出了正向压降温度变化率的理论表达式和实验测量值;并描述了微测辐射热计的设计思路和制作工艺.实验结果表明在室温(284～253K)附近,横向多晶硅p+p-n+结正向压降的温度变化率为1.5mV/K;在3～5μm红外波段,微测辐射热计的电压响应率为5.7×103V/W,黑体探测率D*为1.2×108cm.Hz1/2.W-1.     

基于微纳结构的硅基高速探测器研究进展

传统平面入射型硅基探测器由于近红外吸收系数低,存在响应速度和探测效率的冲突,被认为不适用于短距离光纤通信领域。微纳结构可有效提高等效光程,使入射光被吸收层充分吸收,提高光电器件的量子效率,广泛应用于太阳电池、近红外增强探测器等领域。近期,研究者基于陷光微结构,实现了数据传输速率达20Gb/s以上、与CMOS工艺兼容的硅基高速探测器,展现出了广阔的发展前景。文章对微纳结构的优化设计、制备方法、基于微纳结构的硅基高速探测器的研究进展进行了综述和分析。     

钙钛矿稀土合金锰氧化物p-n异质结

由于稀土合金锰氧化物在电子输运和自旋磁性等方面具有优异特性,人们对其潜在的应用寄予了很高的期望．近5年来,人们发展了一种新型的p-n结结构:在n型掺杂的SrTiO3单晶衬底上生长具有p型性质的钙钛矿锰氧化物薄膜,制成p-n异质结结构．本文重点介绍这种新型p-n异质结的研究进展,并对该类p-n异质结的应用前景进行展望．     

横向多晶硅p+p-n+结非致冷红外焦平面

应用标准CMOS工艺,同时结合体硅微机械加工技术,研制成功横向多晶硅p p-n 微测辐射热计单元;基于研制成功的微测辐射热计,设计了规模为128×128面阵的非致冷红外焦平面.采用标准CMOS工艺制作横向多晶硅p p-n 结热敏响应元和读出电路;在CMOS工艺完成后,辅以与CMOS工艺兼容的体硅微机械加工工艺,制备微桥形式的热绝缘结构,从而方便地实现了CMOS读出电路与探测器阵列的单片集成.在3～5 μm红外波段,微测辐射热计的电压响应率为5.7×103 V/W,黑体探测率D·为1.2×108 cm·Hz1/2·W-1.焦平面采用行读出模式的结构,信号读出采用栅调制积分电路,输出级采用外接负载电阻的源极跟随电路,将探测器单元产生的信号按顺序串行单端输出.     

硅基集成光电子器件的新进展

综述了硅基微纳激光器、调制器、探测器及光传输控制器件的最新研究进展.重点阐述了表面等离子体、量子阱、光子晶体及纳米光栅等新型结构在提高器件综合性能和降低器件尺寸方面的重大作用.同时,还展示了用标准互补金属氧化物半导体(CMOS)技术,实现硅基光子器件和电子器件在同一基片上微纳集成的巨大前景.     

高深宽比硅基微纳结构制造方法及其应用

三维高深宽比硅基结构是基于微纳制造技术的功能载体或执行机构。其由于小尺寸特征而获得特殊的微纳效应,具有灵敏度高、分辨率高、噪声低、位移量小等特点,在光电、生物、微能源和集成互连等技术领域具有广泛应用前景。主要分析了高深宽比硅基微纳结构的种类及特点;系统综述了该结构的制造方法及国内外研究现状;详细描述了不同外形特征结构的应用领域;从工艺标准、建模仿真、批量生产等方面讨论了高深宽比硅基微纳结构制造存在的技术瓶颈问题,并对高深宽比硅基微纳结构的可靠制造与发展趋势进行了展望。     

用激光制造Si太阳电池的p-n结

美国麻省理工学院林肯实验室最近研究成功了利用激光制作p-n结的方法(Electronics,June 16,1981,pp.39—40)。这种方法非常简单,用一步工序就可作成p-n结,而且设备简单,容易实现连续自动化,所以适用于制造Si带状晶体等太阳电池。制     

Efficiency calculations for thin-film polycrystalline semiconductor p-n junction solar cells

Numerical calculations have been made of the effect of grain size on the short-circuit current and the AM1 efficiency of polycrystalline thin-film GaAs and InP (2 µm thick) and silicon (25 µm thick) p-n junction solar cells. Junction solar cells are seen to be more efficient than Schottky-barrier cells, due to the higher dark current associated with Schottky diodes. GaAs shows the highest efficiency and both GaAs and InP attain 90 percent of their maximum efficiencies at a grain size of 10 µm, while silicon requires grain sizes of 200 µm to attain 90 percent of maximum efficiency. However, the deleterious effect of poor lifetimes and mobilities is less for silicon polycrystalline cells than for the direct-bandgap devices.     

Measurement circuits for silicon-diode and solar-cell lifetime andsurface recombination velocity by electrical short-circuit current decay

Two improved switching circuits for transient electrical short-circuit decay are presented that allow more accurate determination of base-region minority-carrier lifetime and back-surface recombination velocity of silicon p-n junction solar cells and diodes. In one circuit, metal-oxide-semiconductor transistors replace the bipolar switching circuit used in the original implementation of the method as described by T.W. Jung, et al. (ibid., vol.ED-31, p.588, 1984). In the other circuit, a pulse generator directly excites the device under study. Comparison of the two circuits by illustrative measurements shows that, in comparison to the original implementation of the method, these versions allow measurement of shorter effective lifetimes, such as those characteristic of low-resistivity (about 0.1 Ω-cm) silicon solar cells     

Silicon solar cells on unidirectionally recrystallized metallurgical silicon

The deposition of a silicon layer containing a p-n junction on a metallurgical silicon substrate has been used for the fabrication of solar cells. The substrate was prepared by the unidirectional solidification of purified metallurgical silicon on a graphite plate, and the active region of the solar cell was deposited by the thermal reduction of trichlorosilane with hydrogen containing appropriate dopants. The current-voltage characteristics of a number of solar cells were measured in the dark and under illumination. The AM1 efficiency of large-area cells (30 cm²) was up to 5.5 percent. When a large-area cell was divided into small-area (5-cm²) ones, the conversion efficiency was found to correlate directly with the dark current-voltage characteristics of, and the structural properties of silicon in, each cell.     

等效表面电荷对台面半导体器件钝化的影响

进一步研究了半导体斜角造型p-n结的表面空间电荷层模型与表面耗尽区模型.计算了耗尽情况下p-n结的表面空间电荷密度,分析了等效表面电荷密度对正斜角造型p-n结表面耗尽区的影响.利用聚酰亚胺和聚酯改性漆钝化的晶闸管电学特性证实了等效表面电荷密度对台面半导体钝化的影响.同时,通过分别采用聚酰亚胺和掺氧多晶硅钝化的高压整流管研究表明,基于掺氧多晶硅的钝化结构具有屏蔽电荷和均匀电场的作用.     

Solar-cell design based on a distributed diode analysis

The front surface of a p-n junction solar cell has resistive losses associated with the diffused layer, the metal-semiconductor contact, and the grid structure. These losses are analyzed by considering the spatially distributed nature of the p-n junction and the grid conductors. This distributed diode analysis is especially useful for solar cells operated under concentrated sunlight conditions. The results show the dependence of the V-I characteristics and the maximum power output per unit cell on the ratio of the diffused layer resistance to the junction dynamic resistance. This ratio can assist the designer in establishing proper grid structure geometries and should tpically be less than 0.1 if the power output per unit cell is to be within 3 percent of that for the lossless case. Experimental measurements are reported which confirm the theoretical calculations. An analysis of the grid conductor losses associated with multiple-connected unit cells shows the disastrous effect that the grid header resistance can have on the performance of a solar cell. The results indicate that the use of a tapered header conductor to decrease the metal coverage may actually worsen cell performance.     

Silicon solar cells produced by corona discharge

A technique for producing p-n junction silicon solar cells has been developed involving the use of a continuous gaseous discharge operating in the corona mode. The process is applicable to the production of p on n or n on p structures. Detailed results are presented for a BF₃ discharge, producing p on n cells, along with preliminary results using a PF₅ discharge, resulting in n on p cells. Efficiencies of over 8% were obtained on single crystal Si p on n cells, and of over 3% for a heavily-defected polycrystalline at AMl without anti-reflective coatings. Fill factors as high as 0.76 were obtained. Analysis of these cells include ion microprobe mass analysis and anodic stripping for concentration profiles, and capacitance-vol tage and current-voltage measurements for electrical characterization. This work was performed under the auspices of the U.S. Energy Research and Development Administration under contract number W-7504-ENG-48.     

A high-low junction emitter structure for improving silicon solar cell efficiency

A new device structure which is designed to substantially increase the open-circuit voltage and the power-conversion efficiency of p-n junction silicon solar cells is described. The structure differs from the conventional cell structure in that it contains a high-low (H-L) junction in the emitter. Based on numerical solutions of the fundamental Shockley differential equations, efficiency improvements of about 15 percent at AM1 and about 40 percent at 50 suns can be epxected. The improvement at 50 suns results in an efficiency of about 20 percent at 27°C.     

高方块电阻发射区单晶硅太阳电池的性能优化

通过提高发射区的方块电阻和优化发射区的磷杂质浓度纵向分布,制备了性能优良的单晶硅太阳电池。I-V测量分析表明:高表面活性磷杂质浓度浅结发射区太阳电池短路电流密度、开路电压和填充因子分别提高了0.32mA/cm2,1.19mV和0.22%,因此转换效率提高了0.22%。内量子效率分析表明:高表面活性磷杂质浓度浅结发射区太阳电池短路电流密度的提高是由于短波光谱响应增强了。SEM分析表明:高表面活性磷杂质浓度浅结发射区太阳电池在发射区硅表面沉积的Ag晶粒分布数量更多、一致性更好,从而更容易收集光生电流传输到Ag栅线,改善了太阳电池的性能。     

Characterization of laser carved micro channel polycrystalline silicon solar cell

In this study the efficiency of polycrystalline silicon solar cells was increased carving micro channel structures using a laser. In research to date, micro channel structures on the surface of polycrystalline silicon solar cells have been manufactured and studied. In an experiment polycrystalline silicon solar cell with micro channel structures on the surface demonstrated an increase in efficiency of 0.23-1.50%, as the radius of the micro channel structures varied from 15 μm to 35 μm. Micro channels also improved the Fill Factor of polycrystalline silicon solar cells. However, the efficiency started to decrease when the radius of the micro channel structures was greater than 40 μm. Detailed features of the variation in current voltage of polycrystalline silicon solar cells with micro channels are discussed.