The fabrication of an electrostatic linear actuator by siliconmicromachining

A microactuator consisting of a plane wafer with striped electrodes covered with an insulation layer and thin cylindrical rollers was designed. When voltage is applied between the striped electrodes and the roller, the electric field between them attracts the roller, causing it to roll. As the roller passes over a striped electrode, the electrode is discharged and another in the forward direction is charged to keep the movement. The electrostatic linear actuator (ESLAC) consists of rollers inserted between a C-shaped stator and a slider that displaces linearly. Silicon micromachining techniques such as lithography, PCVD, and etching were utilized to fabricate the plane wafer. Model actuators were realized on silicon wafers. The performance of the models is examined     

China to install turnkey solar cell fabrication line

GT Solar Technologies of Nashua, New Hampshire, will install a turnkey GT Waffab photovoltaic wafer fabrication line for installation at Baoding Yingli New Energy Resources of Baoding, China.     

The role of silicon solar cell fabrication in intermediate-level PV training

Appropriate regionally-based training is of major importance for improving the market penetration of basic PV systems in developing countries. This communication describes an initiative at a Brazilian university where science and engineering undergraduates are encouraged to fabricate, test, and package crystalline silicon solar cells.     

Integration of screen-printing and rapid thermal processingtechnologies for silicon solar cell fabrication

For the first time, the potentially cost-effective technologies of rapid thermal processing (RTP) and screen-printing (SP) have been combined into a single process sequence to achieve solar cell efficiencies as high as 14.7% on 0.2 Ω-cm FZ and 14.8% on 3 Ω-cm Cz silicon. These results were achieved without application of a nonhomogeneous (selective) emitter, texturing, or oxide passivation. By tailoring the RTP thermal cycles for emitter diffusion and firing of the screen-printed silver contacts, fill factor values >0.79 were realized on emitters with a sheet resistance (ρ_s ) of ~20 Ω/□ and grid shading <6%. Such high fill factors clearly demonstrate that screen-printed contacts can be fired on extremely shallow RTP emitters (x_j=0.25-0.3 μm) without shunting cells. IQE analysis depicts a strong preference for shallow emitter junction depths to achieve optimal short wavelength response of these unpassivated emitters. In some cases, front contacts were printed through plasma enhanced chemical vapor deposited (PECVD) SiN/SiO₂ dielectrics which prevented the shunting of shallow emitters by serving as partial barriers minimizing the diffusion of metallic species from the contacts. The firing of screen-printed contacts through these PECVD films, achieved the multiple purposes of contact formation, efficient front surface passivation due to annealing of the SiN, and high quality antireflection (AR). Research is presently underway to further optimize the RTP emitter design for screen-printing and develop techniques for implementing selective emitter and oxide passivation technologies for higher efficiency cells     

Determination of electrostatic fields and equipotentials using Fredholm's method

The electrostatic field and potential induced by an electrical charge inside a conductive cavity are calculated. First, the density of charge induced on the internal surfaces of the cavity has to be determined. This density is related to the original charge by an integral equation. Then, by the use of Fredholm's method this integral equation is reduced to a conventional system of algebraic linear equations, yielding density values at definite points of the internal surfaces, and hence electrostatic field and potential values at any internal point of the cavity. Fredholm's method is well suited to cavities with internally intricated structure and avoids numerical convergence difficulties.     

Low-OH-content fibre fabrication using particle-size control sol-gel method

By the sol-gel method using a new `particle-size control? technique, a low-OH content at a level of 0.1 parts in 106 and a minimum optical loss of 1.8 dB/km at 1.6 ?m wavelength has been achieved in pure silica core single-mode optical fibres. Improvement of dry gel properties using particle-size control is essential to bubble-free fibre drawing form dehydrated gel-derived glasses.     

The fabrication and application of Zernike electrostatic phase plate

The Zernike electrostatic phase plate (ZEPP) consisting of three ring electrodes and two insulating rings has been fabricated using Micro Electro-Mechanical System processes. The electrostatic field produced in the phase plate was measured by electrostatic force microscopy. The electrostatic field and focal length of the phase plate is calculated using electron optics principles. The comparison of the experimental electrostatic field and the theoretical calculated is discussed. Finally, we report the application of ZEPP to enhance contrast of the SiON(x)/SiO(2) interface in an NMOS semiconductor device. The quantitative analysis of the contrast enhancement versus the applied bias is discussed in detail.     

Some prospective applications of silicon electrodeposition from molten fluorides to solar cell fabrication

Electrodeposition of both epitaxial and polycrystalline continuous films of dense, coherent, and well-adherent silicon coatings was achieved from molten fluorides. A dissolving Si anode and an operating temperature of about 750 C were utilized. Silicon electrocrystallization epitaxy (ECE) produced films with the (111) orientation on Si substrates of the same orientation. The unintentionally doped films were of p-type character with a resistivity in the range 0.05 - 0.10 Ω-cm. Polycrystalline Si films were similarly electroplated onto various polycrystalline metal substrates. Uniform coherent, and well-adherent coatings with grain diameters as large as 40 – 50 μm were obtained. The useful rate of electrodeposition of Si could be significantly increased by the application of an alternating square wave pulse (ASWP)₂technique. Cathodic current pulses as high as 300 mA/cm² (growth rate of about 5 μm/min) were demonstrated. The cathodic current efficiencies, for all modes of growth, were about 70 – 100%. The effects of the various operating parameters, and some prospective applications to the fabrication of solar cells, are discussed. This was paper A-6 in the 18th Annual Electronic Materials Conference, Salt Lake City, June 23–25, 1976.     

CuInSe2薄膜太阳能电池非真空印刷制备技术研究

对CuInSe2(CISe)薄膜太阳能电池的吸收层进行了非真空印刷制备技术研究。使用机械化学法合成CISe前驱粉末,采用ethyl-cellulose作为分散试剂配置印刷浆,使用丝网印刷技术沉淀CISe吸收层,对沉淀的吸收层进行N2氛围的快速热退火处理,使用XRD、UV、SEM及J-V等手段对CISe吸收层进行了分析表征。结果表明:简单高效的机械化学法可获得主(112)晶向CISe前驱粉末;经丝网印刷并干燥后的CISe吸收层中含有大量有机分散剂,退火可蒸发有机分散剂并有效改善CISe结晶度,但过长的退火会增加晶体缺陷;实验制得一典型CISe薄膜太阳能电池的短路电流密度、开路电压、填充因子和转换效率分别为4.48mA/cm2、355mV、0.41和0.65%。     

Submicrometer CMOS device fabrication using an X-ray stepper

CMOS devices with submicrometer minimum features have been fabricated using X-ray/photo hybrid lithography. The device fabrication process utilized thirteen lithography steps, including four X-ray lithography levels, such as local oxidation of silicon (LOCOS) [1], gate, contact, and wiring, that required the most critical dimension control and alignment accuracy. A step and repeat exposure system and a SiNxmembrane mask were used for the X-ray lithography process. The SiNxmembrane mask was improved in its flatness and effective contrast by employing a stress compensating structure and a secondary electron trapping film. As a result, CMOS devices with 0.4-µm effective channel length were fabricated using a single-layer resist process.     

Amorphous/crystalline heterostructure as a novel approach to fabrication of a solar cell

The performance and characteristics of a novel structure device combining amorphous and crystalline semiconductors is reported for the first time. An amorphous SiC:H/crystal Si heterostructure solar cell gave a conversion efficiency of 5.11% with Voc = 0.53 V and Isc = 22.64 mA/cm2 without the use of any transparent electrode or AR coating. The relative spectral response of the cells has been found to be close to that of the `violet cell?.     

Novel fabrication method of quarter-wave-shifted gratings using ECR-CVD SiNx films

Quarter-wave-shifted gratings were fabricated by novel methods using ECR-CVD SiN, films. SiNx films deposited on photoresist and grooves have a higher etching rate than those deposited on the flat substrate. We made good use of this difference to fabricate the quarter-wave-shifted gratings with a 240 nm period, about 150nm depth and narrow transient regions.     

Simple fabrication of perovskite solar cells using lead acetate as lead source at low temperature

We reported a simple one-step, low-temperature solution-processed technique to fabricate perovskite solar cells using lead acetate as the lead source. Solvent annealing was applied for grain growth to obtain better morphology. Uniform perovskite films without pinholes can be obtained by solvent annealing for 5 min at 100 °C. Planar perovskite solar cells based on the high quality perovskite films deliver power conversion efficiency up to 12.71% with negligible hysteresis and good reproducibility. In addition, the substrate surfaces have little effect on the crystallization of perovskite when lead acetate was used, leading to uniform films on different substrates, which can provide a wide choice of substrates and interfacial materials.     

An electrostatic recording method using transformer assemblies based on error-correcting codes

A new high-speed electrostatic recording method has been developed that utilizes assemblies of transformers whose secondary windings are wound on the cores and connected to output terminals in arrangements based on (n,k) or fixed-weight error-correcting codes. This method is used to distribute electrostatic recording pulses to styli to form latent images on recording paper. With the present experimental device a recording speed of 480 kilodots per second, or 436 steps per second, was obtained.     

Organic tandem solar cell using active inter-connecting layer

We developed an active inter-connecting layer (ICL) composed of SnCl₂Pc/Al/F₁₆CuPc/ZnPc to achieve an effective organic tandem solar cell consisting of complementary absorbing layers. This ICL provides a new function to improve the light response of the top cell to enhance current matching between bottom cell and top cell. Meanwhile, the ICL is highly transparent and has efficient charge collections to realize electric connection in series. Finally, in the tandem cell, the open-circuit voltage of 1.52 V is obtained that is the summation of the single cells (1.08 V and 0.46 V), and the power conversion efficiency of 3.21% under 100 mW/cm² is achieved that is higher than those of the single cells.     

Numerical modeling of an amorphous-silicon-based p-i-n solar cell

A simulation program for amorphous-silicon-based p-i-n solar cells which allows for accurate calculation of single-junction or multijunction cell response under monochromatic or global AM1.5 illumination is discussed. The device model is based on a complete set of Poisson and current continuity equations describing the amorphous intrinsic and microcrystalline or amorphous n⁺ and p⁺ contacts. It predicts solar cell behavior with uniform and nonuniform optical (mobility) bandgaps, spatially dependent doping densities, and various layer thicknesses, as demonstrated by the very good agreement between the experimental and simulated current-voltage characteristics of single cells, with the bandgaps in the range of 1.75 to 1.47 eV. The material parameters used in the simulation have been obtained from experimental results reported in the literature. The possibility of obtaining higher efficiencies using novel cell designs has also been investigated. Calculations have been carried out on cell structures in which the bandgap of the intrinsic layer is profiled to help hole transport. The most efficient structure, also confirmed by recent experimental data, incorporates normal profiling throughout the bulk of the intrinsic layer with a thin graded buffer at the p⁺ -intrinsic junction