Towards high‐eficiency silicon solar cells by rapid thermal processing

Abstract

Rapid thermal processing can offer many advantages, such as small overall thermal budget and low power and time consumption, in a strategy focused on cost‐effective techniques for the preparation of solar cells in a continuous way. We show here that this very short duration (a few tens of seconds) of isothermal heating performed in a lamp furnace can be used for many thermal steps of silicon solar cell processing. Rapid thermal processing was applied to form the p‐n junction from a phosphorus‐doped spin‐on silica film deposted on (100) silicon substrates at typical processing temperatures between 800 and 1100°C. the solar cells showed conversion efficiencies as good as those processed in a conventional way.

Formation of shallow boron emitters in crystalline silicon using flash lamp annealing: Role of excess silicon interstitials

“…The values of a tilt for sample A are comparable to those reported ($20 arc sec) for ZnO layers grown on c-sapphire by PA-MBE utilizing a MgO/ZnO buffer bilayer followed by annealing at 750 C prior to the ZnO film deposition. 34 Similarly, also the large L k $ 3 lm confirms the good crystallographic property of sample A. On the other hand, for sample B, both a tilt and L k are in the range of the values generally reported for heteroepitaxially grown ZnO layers.…”

“…Here, it is also worth pointing out that rocking curves showing similar characteristics have also been reported for ZnO films grown by PA-MBE on c-sapphire substrate. 34 In this case, interfacial degradation due to the large lattice mismatch to the substrate was discussed as a possible reason for the double peak feature. However, in our case, the absence of a double peak for the high order reflections excludes the occurrence of a two region structure along the growth direction, as expected, since no lattice mismatch is present.…”

“…On the other hand, for sample B, both a tilt and L k are in the range of the values generally reported for heteroepitaxially grown ZnO layers. 34,38,39 The RSM results of the asymmetrical À10.5 reflection are shown in Figs. 5(a) and 5(b).…”

“…A common strategy in industry for fabricating emitters is through diffusion from a gas source in a tube furnace [31,32], but this requires prolonged heat treatments which deepens the emitter and reduces the blue response. Several rapid heat treatment schemes such as RTA [29,33,34], Excimer Laser Annealing (ELA) [35,36] and FLA [28,37] have successfully been employed to realize very shallow emitters with high doping concentrations. Perhaps the most efficient of these is ELA where a high intensity laser melts a very thin layer (∼ 150 nm [38]) close to the surface greatly enhancing the diffusion of dopants producing a box like diffusion profile with very high dopant concentrations.…”

“…However, this technique requires expensive low energy ion implantation and suffers from low throughput since the laser only heats the wafer locally. A higher throughput strategy for fabricating shallow emitters is using RTA to heat up wafers and in-diffusing dopants from a surface source [29,33,34]. This technology has the advantage of being able to treat several wafer simultaneously in a matter of seconds, but as seen in the inset of Fig.…”