Solar Cell Emitters Fabricated by Flash Lamp Millisecond Annealing

Abstract

Phosphorus ion implantation was used for the emitter formation in mono-and multicrystalline silicon solar cells. After ion implantation the silicon is strongly disordered or amorphous within the ion range. Therefore subsequent annealing is required to remove the implantation damage and activate the doping element. Flash-lamp annealing offers here an alternative route for the emitter formation at overall low thermal budget. During flash-lamp annealing, only the wafer surface is heated homogeneously to very high temperatures at ms time scales, resulting in annealing of the implantation damage and electrical activation of phosphorus. However, variation of the pulse time also allows to modify the degree of annealing of the bulk region to some extent as well, which can have an influence on the gettering behaviour of metallic bulk impurities. The µ-Raman spectroscopy showed that the silicon surface is amorphous after ion implantation. It could be demonstrated that flash-lamp annealing at 800• C for 20 ms even without preheating is sufficient to recrystallize implanted silicon. The highest carrier concentration and efficiency as well as the lowest resistivity were obtained after annealing at 1200• C for 20 ms both for mono-and multicrystalline silicon wafers. Photoluminescence results point towards P-cluster formation at high annealing temperatures which affects metal impurity gettering within the emitter.

The effect of millisecond flash lamp annealing on electrical and structural properties of ZnO:Al/Si structures

“…A similar redistribution is also obtained for O (data not shown) and Al, suggesting a broadening of the interfacial region. Also, Zn redistributes after the FLA at 37 J/cm 2 (Fig. 2(a)), and the width of the Zn peak after 41 J/cm 2 is similar to that of the Si peak.…”

“…1 In this context, novel annealing techniques, such as flash lamp annealing (FLA), represent an exciting possibility to reduce the manufacturing cost of large area opto-electronic devices and also improve their performance. 2 In order to substitute ITO with ZnO, equivalent or lower electrical resistivity of the film is required. There has been a substantial amount of work dedicated to reduce the resistivity of highly doped n-type ZnO films during the past decade and some groups have reported ZnO films with a resistivity less than 2 Â 10 À4 X cm.…”

Formation of silicon nanocrystals in silicon carbide using flash lamp annealing

“…Only layers on Si substrates were treated by RTA. The FLA setup used in this work was described by Prucnal et al [18]. The setup features an RTA system for backside preheating and an FLA system for front-side heating.…”

“…(blue) and Si0.77C0.23 (green) (left-hand ordinate) with the normalized intensity of the FLA Xe lamps I(λ) [18] (right-hand ordinate). Figure 11 b) Si0.63C0.37 compared with that in Si0.77C0.23.…”

Insights to emitter saturation current densities of boron implanted samples based on defects simulations

“…Regardless of the concern over defects, the use of ion implantation [1][2][3][4][5][6] and annealing [7] applied to solar cells has been studied for many years. Lifetime degradation due to ion implantation induced defects has been explained in terms of near-surface stable dislocation loops, as well as deeply-penetrating defects that result in uniformly-degraded lifetimes up to a depth of 100 ȝm [5].…”