An introduction to gold gettering in silicon

Abstract

Metals, and particularly gold, introduce electrical states into silicon which act as traps for charge carriers. While this is desirable in some devices, in others it degrades performance and must be removed by gettering. This paper discusses the problem, and presents experimental studies on the mechanism of intrinsic gettering of gold.

Not All That Glitters Is Gold: Metal-Migration-Induced Degradation in Perovskite Solar Cells

“…This unexpected occurrence of the high Au peak is the first ever reported direct evidence of metal migrating from the electrode to inside the perovskite layer. This phenomenon, however, has been observed previously in inorganic semiconductors for several different metals such as Au, Ag, Ni, Cu, and Fe. − Figure b presents the 3D distribution of the ions shown in Figure a across a 100 μm 2 region of the samples (see Movie S1 for an animated 3D reconstruction). One can clearly see that the respective ions are distributed uniformly in the xy plane of the device.…”

“…Indeed, we observe a severe, irreversible reduction in V oc , J sc , and FF in the devices aged at high temperature. The phenomenon of Au creating mid-band-gap states for silicon devices has been reported before. , …”

“…The phenomenon of Au creating mid-band-gap states for silicon devices has been reported before. 36,37 In order to pinpoint the observed degradation to Au diffusion into perovskite and to exclude possible influence of interfacial or HTL degradation, we performed dark heating experiments on two identically fabricated devices, one of which had the Au electrode temporarily removed for the duration of the heating phase (see Methods). We found that the device heated without the Au electrode did not degrade significantly and later recovered almost all of its initial performance (Figure 4a).…”

“…This unexpected occurrence of the high Au peak is the first ever reported direct evidence of metal migrating from the electrode to inside of the perovskite layer. This phenomenon, however, has been observed previously in inorganic semiconductors for several different metals such as Au, Ag, Ni, Cu and Fe [36][37][38][39][40] . Based on the evidence (ToF-SIMS, ICP-MS) it was concluded that Au from the top electrode can diffuse across the organic Spiro-MeOTAD HTL and into the perovskite before it is stopped at the TiO 2 /perovskite interface.…”