Photocurrent and diffusion lengths at the vicinity of grain boundaries (g.b.) in N and P-type polysilicon. Evaluation of the g.b. recombination velocity)

Abstract

2014 Les photocourants, les longueurs de diffusion (L) et les vitesses de recombinaison aux joints de grains (s) ont été mesurés à l'aide d'un système de balayage optique sur des échantillons de silicium polycristallin de type N et P. Selon le type des grains, L varie entre 5 03BCm et 150 03BCm et s est supérieur à 104 cm.s-1. Les resultats concernant les mesures locales des longueurs de diffusion montrent qu'au voisinage des joints de grains s'exercent des fortes contraintes. Il semble que les potentiels de barrière aux joints de grains sont plus importants dans les échantillons de type N que dans ceux de type P pour expliquer la plus grande activité recombinante des joints de grains dans le silicium polycristallin de type N que dans celui de type P.

Comparing n- and p-type polycrystalline silicon absorbers in thin-film solar cells

“…We performed activation energy measurements on lowly doped n-(2.4 ⋅ 10 16 cm −3 arsenic) and p-type (1.0 ⋅ 10 16 cm −3 boron) polycrystalline silicon layers, finding values of 0.48 eV and 0.26 eV, respectively. The fact that we found the activation energy of n-type polysilicon layers significantly higher than that of similar p-type polysilicon layers, despite their similar structure and doping levels, is consistent with the literature [46]. This is due to the Fermi level being pinned at the grain boundaries closer to the valence band than the conductance band in both n-and p-type polycrystalline silicon, which has been suggested as a major effect of dangling bonds in the formation of depletion-type grain boundaries in both n-and p-type polycrystalline silicon [47].…”

Back Illuminated N/P/P<sup>+</sup> Bifacial Silicon Solar Cell under Modulated Short-Wavelength: Determination of Base Optimum Thickness

“…3) The diffusion lengh (L) giving the distance traveled by the photogenerated carriers [37] [38], for a time (τ) that is their lifetime [39] [40] [41], with the diffusion (D) [42] and mobility (μ) [43] coefficients 4) the excess minority carriers recombination that occurs in the volume is associated with the lifetime (τ) and that on the surfaces [44] are called surface recombination velocity, (Se at the n + front, Sf at the junction n + /p, Sb at the rear p/p + , and Sg at the grain joints in the 3D model) [45] [46] [47] [48] [49].…”

Shunt Resistance Determination in a Silicon Solar Cell: Effect of Flow Irradiation Energy and Base Thickness

“…Theoretically, the investigation is done by considering the crystallographic aspect i.e., in a one-dimensional (1D) [29] or three-Dimensional (3D) model of space [30]. The latter case takes into account the grain size (g) and the grains boundaries recombination velocity (Sbg), which influence the shunt resistance [31] [32]. Regardless of the model used [33], the recombination rate at the junction (x = 0) and in the rear (x = H) in the base of the solar cell, is taken into account through, respectively the surfaces recombination velocity Sf and Sb [34] [35] [36].…”