Transmission electron microscopy study of hydrogen defect formation at extended defects in hydrogen plasma treated multicrystalline silicon

Abstract

Hydrogenation of multicrystalline silicon for solar cell applications is considered to be an effective method of increasing the lifetime by passivating defects and impurities. Hydrogen plasma treated as-cut and chemically etched multicrystalline silicon samples have been studied by electron microscopy in order to investigate hydrogen defect formation at extended bulk defects. In chemically etched samples, the texture of the surface after hydrogen plasma treatment differs between different grains depending on grain orientation. In as-cut samples, hydrogen induced defects are formed on sawing defects that extend up to ∼5 μm below the Si surface. Intragranular defects are also observed in the ∼1 μm subsurface region. The density of defects is higher in as-cut samples than in chemically etched samples and the size of the defects increases with depth. Hydrogen induced structural defects on bulk dislocations and on dislocations in twin grain boundaries and stacking faults are found several microns below the sample surface. It is concluded that (i) the passivation efficiency of multicrystalline silicon substrates after H plasma treatment can be limited by the formation of hydrogen induced structural defects and that (ii) such defects can be used to getter unwanted impurities upon high temperature processing of the Si wafers.

Room temperature all‐silicon photonic crystal nanocavity light emitting diode at sub‐bandgap wavelengths

“…b), whose mean diameter is about 10–15 nm, occupying the (100) plane (parallel to the surface) and the {111} planes. Similar platelets were observed in refs , , . A high resolution image of a few platelets is shown in the top left inset in Fig.…”

One‐step formation of nanostructures on silicon surfaces using pure hydrogen‐radical‐initiated reactions

“…From the point of device applications, surface damage by hydrogen‐radical treatment is an important issue. Defect formation by hydrogen‐radical treatment using a PECVD reactor has been reported by Nordmark et al . In processing at temperatures <400°C, hydrogen‐radical treatment creates crystalline defects since excess hydrogen radicals diffuse into the subsurface area of the silicon, causing formation of hydrogen‐related bubbles and voids .…”

“…The process consists of particle deposition with high filament current and hydrogen‐radical treatment for the surface etching process. The WSi 2 particles are generated by a gas‐phase reaction between evaporated tungsten and silicon hydride that was generated by a reaction between silicon and hydrogen radicals . In this paper, we report the one‐step preparation of such silicon nanostructures as inverted pyramid texture, V‐groove texture, dense fine silicon nanowire growth over texture, and nanosheet structure can be obtained using a set of hydrogen‐initiated reactions: hydrogen with tungsten, Si and tungsten silicide.…”

Si substrates texturing and vapor-solid-solid Si nanowhiskers growth using pure hydrogen as source gas

“…[35][36][37] One advantage of this method is that it also can texture ͕111͖ silicon and, therefore, has potential for texturing mc Si. 35 This is in contrast to pure hydrogen plasma treatments, [38][39][40][41][42][43][44][45][46][47][48] where texturing depends on grain orientation and hydrogen induced structural defects form in the bulk. [38][39][40][41][42][43][44][45][46][47][48] In the tungsten hot filament case, the high temperature, ϳ800°C ͑in contrast to ϳ250°C for H-plasma treatments [43][44][45][46][47] ͒, prevents hydrogen defect formation in the bulk.…”