In this contribution, we focus on a well-known complex in hydrogenated silicon, the hydrogen-boron (HB) pair, which allows us to directly determine the absolute hydrogen concentration in the silicon bulk via resistivity measurements. We demonstrate here that HB-pairs, which were formed during dark annealing, disappear under illumination at elevated temperatures. Upon a subsequent dark anneal, HB-pairs form again. Our experimental results suggest a reversible process for the formation of HB-pairs from H_2 dimers upon dark annealing and the reformation of H_2 dimers upon illuminated annealing. In addition, we show that the time of HB-pairs disappearance depends critically on the temperature and the applied illumination intensity, suggesting a thermally activated electron-enhanced backward formation of hydrogen dimers. Importantly, we observe on our samples made of boron-doped float-zone silicon (FZ-Si), that the loss of HB-pairs is accompanied by a reduction in carrier lifetime, which needs to be accounted for when describing the HB-loss curves, since the excess carrier concentration varies accordingly over time. In addition, our results might point to a connection between light-induced degradation and HB dissociation, which, has however to be examined in more detail in future studies.
展开▼
