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Light-induced electroless plating (LIEP) is an easy and inexpensive method that has been widely used for seed layer deposition of Nickel/Copper (Ni/Cu)-based metallization in the solar cell. In this study, material characterization aspects of the Ni seed layer and Ni silicide formation at different bath conditions and annealing temperatures on the n-side of a silicon diode structure have been examined to achieve the optimum cell contacts. The effects of morphology and chemical composition of Ni film on its electrical conductivity were evaluated and described by a quantum mechanical model. It has been found that correlation exists between the theoretical and experimental conductivity of Ni film. Residual stress and phase transformation of Ni silicide as a function of annealing temperature were evaluated using Raman and XRD techniques. Finally, transmission line measurement (TLM) technique was employed to determine the contact resistance of Ni/Si stack after thermal treatment and to understand its correlation with the chemical-structural properties. Results indicated that low electrical resistive mono-silicide (NiSi) phase as low as 5 mΩ.cm2was obtained.

Texturing of a mono crystalline Si wafer aims to create light trapping structures to reduce the reflection losses. Being a cheap and efficient process, alkaline texturing of Si wafers is commonly used in all industrial mono crystalline solar cell production lines. However, standard process with potassium hydroxide (KOH)‐based solutions with isopropyl alcohol (IPA) addition suffers from instability, high material consumption, and nonuniformities in the shape and the distribution of the pyramid structures formed on the Si surface. In this work, we studied the effect of ultrasonic agitation (UA) during the etching process on the structural, optical, and electrical properties of mono crystalline Si solar cell as a function of process parameters. We have shown that UA improves optical and electrical performance of the cells by forming uniform pyramid structures. In addition, it also helps to lower the material consumption and Si removal from the surface by enabling less process time and temperature. Ultrasonic agitation of the etching solution proves to be a good modification of the wet process steps for the mono crystalline silicon solar cell technology.

Metal-assisted etching (MAE) can be used to form antireflective and light-trapping structures on crystalline silicon solar cells. This method has been widely used to form nanowires and nanoholes on their surfaces. In this study, the MAE technique with additional hole-injection mechanisms has been investigated to form surface nanostructures with various shapes. The effect of each chemical's percentage, as well as the etching time, has been studied on the surface geometry and optical performance. The average reflection from the surface was reduced to less than 3% over the solar spectrum. The light-trapping properties of the structures were investigated through absorption measurements on thin wafers, and a nearly 90% average absorption was obtained for samples with a 50-μm thickness. The smoothing of the surface and lifetime of the chemical solutions has been systematically studied. As a result, control over the surface geometry and optical properties have been obtained with this new single-step etching approach. Passivation of the surface with SiO2 is also investigated to realize device implementation in the next step.

Aluminum‐induced crystallization (AIC) experiments were carried out in order to investigate the influence of vacuum annealing of the Al layer at 500 °C prior to deposition of e‐beam evaporated amorphous silicon (a‐Si). A control sample set using the identical deposition sequences but without the Al vacuum anneal was also produced as reference. Analysis revealed that after vacuum annealing, the Al grain size increases significantly. The surface Al‐oxide layer thickness is reduced, however, the Al‐oxide to metallic Al ratio is increased in this layer. Following a‐Si deposition, the a‐Si/Al/SiNx/glass stacked samples were annealed in N2atmosphere at temperatures between 420 and 450 °C. It was seen that the crystal growth rate in the samples with vacuum‐annealed Al is significantly reduced compared to the control samples, due to the reduction of Al grain boundary density.

As photovoltaic (PV) energy continues to gain market penetration due to the lower cost of PV modules, attention is shifting to the balance of system. In this paper, a new efficiency evaluation technique based on a usage model that is synthesized from high-temporal operational data of a PV module is investigated, along with a multiobjective design optimization of the dc-dc stage of a module-integrated inverter. The analysis shows that the technique provides more accurate results than the California Energy Commission weighted efficiency method, particularly when other geographic regions of the world are considered.

The standard Schottky noise approach alone is not sufficient to describe the noise mechanism in an InAs/GaSb superlattice photodetector at reverse negative bias. The additional noise identified appears at surface activation energies below 60 meV and is inversely proportional to the reverse bias. In order to satisfactorily explain the experimental data, we hereby propose the existence of a surface recombination noise that is a function of both the frequency and bias. The calculated noise characteristics indeed show good agreement with the experimental data.

Absorption of the light by a solar cell can be improved significantly by light trapping structures formed on the front surface of the device. In particular, thin crystalline and amorphous solar cells are expected to benefit from the improved light absorption in a region closer to the surface of the cell. Recently, we have shown that vertically aligned silicon (Si) nanowires formed on flat (100) Si wafer surface by metal assisted etching can effectively be used for this purpose. In this paper we present demonstration of nanowire application to industrial size solar cell system and a comparison between flat and pyramid textured Si wafers. Standard procedures were followed to fabricate solar cells with and without Si nanowire process on mirror like and pyramid textured Si wafers. The dependence of the solar cell parameters on the process parameters was studied systematically. Reflection spectra showed successful light trapping behavior on the surface of the cells. In all samples, we have obtained excellent current-voltage (I-V) characteristics with high fill factors. However, the efficiency of the cells was found to decrease with the etch duration. This can be attributed to the increased recombination along the nanowires or increased surface area due to the roughening of the surface after etching process.