Bifacial p-Type PERC Solar Cell with Efficiency over 22% Using Laser Doped Selective Emitter

In this paper, we report one bifacial p-type PERC solar cell with efficiency over 22% using laser doped selective emitter produced in larger-scale commercial line on 6-inch mono-crystalline wafer. On front side of the solar cell, square resistance of p-n junction was found to be closely related with laser power at certain laser scan speed and frequency. On the other side, the rear fingers with different ratios of height and width and rear silicon nitride (SiNx) layer with different thickness were optimized, and a highest rear efficiency of the bifacial solar cell was obtained. Finally, bifacial silicon solar cells with the front and rear efficiencies exceeding 22% and 15% (AM1.5, 1000 W/m2, 25 °C) were successfully achieved, respectively.

Improvement of GaN crystalline quality by SiNx layer grown by MOVPE

In this work the mechanism which helps to reduce the dislocation density by deposition of a SiNx interlayer is discussed. It is shown that the dislocation reduction by SiNx interlayer deposition is influenced by dislocation density in the underlying GaN layers. The SiNx interlayer is very effective when the original dislocation density is high, while in the case of lower dislocation density the deposition of SiNx is not effective for crystal quality improvement. Although it is widely accepted that SiNx serves as a barrier for dislocation propagation, similarly to the enhanced lateral overgrowth method, it is shown that after masking the SiNx deposition cannot be the dominant dislocation reduction mechanism. The most probable mechanism is the annihilation of bended neighbouring dislocations during the coalescence of 3D islands. The SiNx layer cannot serve as a barrier for dislocations, since it is probably dissolved during the following GaN growth and dissolved Si atoms are incorporated into the above-grown GaN layer which stimulates the 3D island formation. Then the use of the SiNx interlayer for dislocation reduction is recommended only for the improvement of layers with a high dislocation density. On the other hand, the PL signal was strongly enhanced for both low and high dislocation density structures with the SiNx interlayer, suggesting that the interlayer might help to suppress the nonradiative recombination in subsequent GaN that is not related to the dislocation density, which remained the same. But its origin has to be studied further.

Study on Correlate Qualitatively the Deposition Conditions with the Morphology of the Nanocomposite Films

In the Nb–Si–N films, Si content (CSi) was varied in each series by changing the power applied on the Si target, whereas the power on the Nb target was kept constant. The microstructure of the coatings was examined by XRD and in cross-section by transmission electron microscopy (TEM). Depending on TS and pN2, the deposition rate showed significant variations from 0.04 to 0.18 nm/s. The correlation between film morphology (preferential orientation of crystallites, grain size, column dimensions, thickness of the SiNx layer covering NbN crystallites) and the deposition conditions (power applied on Si target, temperature, nitrogen partial pressure and deposition rate) provides useful information for optimizing the deposition process.