激光预处理对增透膜阈值的影响

激光预处理是提高光学薄膜激光损伤阈值的有效方法之一。本文就激光预处理前后增透膜损伤阈值的变化、破斑深度的变化、膜层中电场分布情况，分析了激光预处理对阈值的影响及原因。     

Silicon solar cells with antireflection diamond-like carbon and silicon carbide films

Optical properties of diamond-like carbon and silicon carbide (SiC) films in dependence on deposition conditions were investigated. It was established that the films having refractive index from 1.6 to 2.3 may be obtained. The film optical bandgap and hardness may be changed from 1.5 to 4 eV and from 1 to 20 GPa, correspondingly. The films were deposited onto the front side of silicon solar cells (SCs). It has been shown that deposition of single- or two-layer diamond-like carbon antireflection (AR) coatings enables the SCs efficiency to be improved 1.35–1.5 times. The improvement is connected with decreasing of reflection losses and passivation of recombination active centers. SiC AR coatings improve the solar cell efficiency up to 1.3 times.     

Design of porous silicon/PECVD SiOx antireflection coatings for silicon solar cells

The meso-porous silicon (PS) has become an interesting material owing to its potential applications in many fields, including optoelectronics and photovoltaics. PS layers were grown on the front surface of the n⁺ emitter of n⁺-p mono-crystalline Silicon junction. The thickness and the porosity of the PS layer were determined by an ellipsometer, as a function of time duration of anodization, and the variation law of the PS growth kinetics is established. Single layers PS antireflection coating (ARC) achieved around 9% of effective reflectivity in the wavelength range between 400 and 1000 nm on junction n⁺-p solar cells. To reduce the reflectivity and improve the stability and passivation properties of PS ARC, silicon oxide layers were deposited by PECVD on PS ARC. SiO_x layers of thickness of 105 nm combined with PS layer led to 3.8% effective reflectivity. V_oc measurements were carried out on all the samples by suns-V_oc method and showed an improvement of the quality of the passivation brought by the oxide layer. Using the experimental reflectivity results and taking into account the passivation quality of the samples, the PC1D simulations predict an enhancement of the photogenerated current exceeding 44%.     

Fabrication of nanoporous antireflection surfaces on silicon

After the surface of a silicon wafer has been texturized, the reflectance of the wafer surface can be reduced to increase the power generation efficiency of a silicon-based solar cell. This study presents the integration of self-assembled nanosphere lithography (SANSL) and photo-assisted electrochemical etching (PAECE) to fabricate a nanostructure array with a high aspect ratio on the surface of silicon wafer, to reduce its reflectance. The experimental results show that the etching depth of the fabricated nanopore array structure is about and its diameter is about 90 nm, such that the aspect ratio of the pore can reach about 68:1. The weighted mean reflectance of a blank silicon wafer is 40.2% in the wavelength range of 280-890 nm. Five-minute PAECE without SANSL reduces the weighted mean reflectance to 5.16%. Five-minute PAECE with SANSL reduces the weighted mean reflectance to 1.73%. Further coating of a 200 Å thick silicon nitride layer on the surface of a nanostructure array reduces the weighted mean reflectance even to 0.878%. The novel fabrication technology proposed in this study has the advantage of being low cost, and the fabricated nanostructure array can be employed as an antireflection structure in single crystalline silicon solar cells.     

半导体行波光放大器

光通信的发展促进了光放大器的研究,半导体行波光放大器目前看来是最有前途的光放大器,因为它结构简便,需要外加的功率小,频带十分宽。本文首先讨论在半导体光放大器两端的防反射膜问题;其次讨论放大器的性能,如增益性能饱和、噪声、增益受偏振的影响;接着讨论放大器在使用中的问题:作为光接收机的前置放大器、级联使用问题和作为光纤通信系统中的中继器问题;最后,文中提出光放大器目前的改进方向及远景研究问题。     

GaAlAs激光器腔面减反射涂层

通过对波长９１０ｎｍ ＧａＡｓ／ＧａＡｌＡｓ激光器谐振腔面蒸镀ＺｒＯ２膜的工艺过程，从理论和实验上分析了涂层特性，透射率由无膜时６２％提高到蒸镀膜后的９４％以上，提高了激光器的激光输出功率和工作寿命，对器件端面起到了保护作用。     

Fabrication of anti‐reflection coatings on plastics using the spraying layer‐by‐layer self‐assembly technique

Abstract— Anti‐reflection (AR) coatings on plastic substrates have been extensively investigated with the development of large‐area LCD and LED displays. A robust AR coating on plastics requires strong adhesion to the substrate, precise thickness and refractive index, and abrasion resistance. In this paper, abrasion‐resistant AR coatings were fabricated on polycarbonate substrates using the layer‐by‐layer spraying deposition of poly(allylamine hydrochloride) (PAH) and silica nanoparticles. The adhesion between the substrates and coatings was enhanced by treating the polycarbonate surfaces with aminopropyltrimethoxylsilane (APTS). The porous low‐refractive‐index PAH/silica‐nanoparticles multilayers were constructed by the layer‐by‐layer spraying of PAH and silica‐nanoparticles aqueous solutions onto the functionalized substrates. The subsequent treatment of the porous coatings with tetrahydroxylsilane leads to stable abrasion‐resistant AR coatings. The resultant AR coatings can reduce the reflection from 5 to 0.3%. The reported technique provides a cost‐effective method for large‐scale production of AR coatings on plastic substrates.     

Efficiency improvement of silicon solar cells enabled by ZnO nanowhisker array coating

An efficient antireflection coating is critical for the improvement of silicon solar cell performance via increased light coupling. Here, we have grown well-aligned ZnO nanowhisker (NW) arrays on Czochralski silicon solar cells by a seeding-growth two-step process. It is found that the ZnO NWs have a great effect on the macroscopic antireflection effect and, therefore, improves the solar cell performance. The ZnO NW array-coated solar cells display a broadband reflection suppression from 500 to 1,100 nm, and the minimum reflectance smaller than 3% can easily be achieved. By optimizing the time of ZnO NW growth, it has been confirmed that an increase of 3% relatively in the solar cell efficiency can be obtained. These results are quite interesting for the application of ZnO nanostructure in the fabrication of high-efficiency silicon solar cells.     

Fabrication of silicon nanowire arrays based solar cell with improved performance

We report fabrication of solar cell (n⁺-p-p⁺ structure) on black silicon substrates consisting of silicon nanowire (SiNW) arrays prepared by Ag induced wet chemical etching process in aqueous HF-AgNO₃ solution. SiNW arrays surface has low reflectivity (<5%) in the entire spectral range (400-1100 nm) of interest for solar cells. The solar cells were fabricated by conventional cell fabrication protocol. Performance of three types of cells, namely cell with SiNW over the entire front surface, cell with SiNW only in the active device area and control cell (on planar surface), has been compared. It was found that cell based on selectively grown shorter length SiNW arrays has the best cell performance.     

Broadband antireflective silicon nanostructures produced by spin-coated Ag nanoparticles

We report the fabrication of broadband antireflective silicon (Si) nanostructures fabricated using spin-coated silver (Ag) nanoparticles as an etch mask followed by inductively coupled plasma (ICP) etching process. This fabrication technique is a simple, fast, cost-effective, and high-throughput method, making it highly suitable for mass production. Prior to the fabrication of Si nanostructures, theoretical investigations were carried out using a rigorous coupled-wave analysis method in order to determine the effects of variations in the geometrical features of Si nanostructures to obtain antireflection over a broad wavelength range. The Ag ink ratio and ICP etching conditions, which can affect the distribution, distance between the adjacent nanostructures, and height of the resulting Si nanostructures, were carefully adjusted to determine the optimal experimental conditions for obtaining desirable Si nanostructures for practical applications. The Si nanostructures fabricated using the optimal experimental conditions showed a very low average reflectance of 8.3%, which is much lower than that of bulk Si (36.8%), as well as a very low reflectance for a wide range of incident angles and different polarizations over a broad wavelength range of 300 to 1,100 nm. These results indicate that the fabrication technique is highly beneficial to produce antireflective structures for Si-based device applications requiring low light reflection.