Rapid Thermal Annealing and Hydrogen Passivation of Polycrystalline Silicon Thin-Film Solar Cells on Low-Temperature Glass

The changes in open-circuit voltage (V-oc), short-circuit current density (J(sc)), and internal quantum efficiency (IQE) of aLuminum induced crystallization, ion-assisted deposition (ALICIA) polycrystalline silicon thin-film solar cells on low- temperature glass substrates due to rapid thermal anneal (RTA) treatment and subsequent remote microwave hydrogen plasma passivation ( hydrogenation) are examined. Voc improvements from 130mV to 430mV, J(sc) improvements from 1.2mA/cm(2) to 11.3mA/cm(2), and peak IQE improvements from 16% to >70% are achieved. A 1-second RTA plateau at 1000 degrees C followed by hydrogenation increases the J(sc) by a factor of 5.5. Secondary ion mass spectroscopy measurements are used to determine the concentration profiles of dopants, impurities, and hydrogen. Computer modeling based on simulations of the measured IQE data reveals that the minority carrier lifetime in the absorber region increases by 3 orders of magnitude to about 1 nanosecond (corresponding to a diffusion length of at least 1 mu m) due to RTA and subsequent hydrogenation. The evaluation of the changes in the quantum efficiency and V-oc due to RTA and hydrogenation with computer modeling significantly improves the understanding of the limiting factors to cell performance. Copyright (C) 2007 Mason L. Terry et al.