Minority Carrier Recombination Properties of Crystalline Defect on Silicon Surface Induced by Plasma Enhanced Chemical Vapor Deposition

Abstract

This research investigates the carrier recombination properties of a crystalline defect layer introduced by the plasma enhanced chemical vapor deposition (PECVD) process of amorphous hydrogenated silicon nitride (SiNx) passivation films. A direct PECVD technique was used for SiNx films deposition. A crystalline defect layer existed on the surface of the silicon substrate and is under the SiNx passivation film. The recombination lifetime in this defect layer was obtained by focusing on the thickness of the defect layer and the effective lifetime before and after the defect layer etching. After etching a few nanometer thickness, effective lifetime drastically increased. On the other hands, the carrier recombination center could be electrically inactivated by 600°C annealing after SiNx deposition. According to the depth profile of effective lifetime, it was clarified the high carrier recombination region were concentrated near the surface of silicon substrate.

UV‐induced degradation of high‐efficiency silicon PV modules with different cell architectures

“…To avoid carrier recombination at defects and improve minority carrier lifetimes, the cell surfaces are generally passivated using dielectric layers, such as hydrogenated silicon nitride (Si x N y :H) and/or silicon dioxide (SiO 2 ). However, UV exposure can disrupt this surface passivation by damaging the passivation layer itself or the passivation layer/Si cell interface 11–14 as well as causing subsurface damage in the silicon 15,16 . Different research groups have identified distinct wavelengths in the 300–400 nm spectral range as the damaging wavelengths of incident radiation for UV degradation of Si solar cells 13,14,17–24 …”

“…However, the recombination velocity at this region is increased by the UV irradiation, resulting in a decrease in carrier lifetime. Another paper revealed that subsequent etching and removal of the damaged passivation and defect layer tend to recover the carrier lifetime 16 . Further, the defects in the damaged layer were electrically inactivated due to high‐temperature annealing (600°C) and thereby resulting increase in the effective lifetime 32…”

“…However, UV exposure can disrupt this surface passivation by damaging the passivation layer itself or the passivation layer/Si cell interface [11][12][13][14] as well as causing subsurface damage in the silicon. 15,16 Different research groups have identified distinct wavelengths in the 300-400 nm spectral range as the damaging wavelengths of incident radiation for UV degradation of Si solar cells. 13,14,[17][18][19][20][21][22][23][24] Emerging higher performance cell technologies, such as p-type passivated emitter and rear contact (p-PERC) and n-type passivated emitter rear totally diffused (n-PERT) cells, have been observed to be more sensitive to UV radiation.…”

“…Another paper revealed that subsequent etching and removal of the damaged passivation and defect layer tend to recover the carrier lifetime. 16 Further, the defects in the damaged layer were electrically inactivated due to high-temperature annealing (600 C) and thereby resulting increase in the effective lifetime. 32 The generation of hot carriers (either electrons or holes) is another proposed UV damage mechanism.…”

Enhanced surface passivation of predictable quantum efficient detectors by silicon nitride and silicon oxynitride/silicon nitride stack

“…Thus, the parametrization of Auger in the simulations can affect the shape of the curve. 18 Furthermore, it must be noted that the simulation structure has not implemented a damaged layer at the interfaces 19 and that the surface recombination model is based on SRH for a mid-gap single level defect. The simplification of the simulation model can also affect the shape of the curves.…”