We fabricated a silicon-wafer based p-n junction solar cell with conversion efficiency of 11% without conventional doping of the emitter or the use of anti-reflecting coatings. The emitter was originally nanocrystalline, grown on n-type crystalline Si and covered with a thin semi-transparent Al layer. Annealing in nitrogen at 430 °C promoted a simultaneous aluminum (Al)-induced recrystallization and Al-doping of the emitter. The recrystallized emitter consisted of considerably larger Si grains which were epitaxially crystallized on the Si substrate. These two effects led to a considerable improvement of the electrical and photovoltaic properties of the resulting p-n junction. © 2013 AIP Publishing LLC.

In this study, we investigated the lateral electrical transport and photocurrent mechanisms in multilayers of two-dimensional arrays of silicon nanocrystals (SiNCs), grown on quartz substrates by low pressure chemical vapor deposition (LPCVD) of Si and thermal oxidation. At low voltages, electrical conduction was ohmic, whereas at higher voltages, it was space charge limited in the presence of traps. At temperatures higher than 200 K both dark current and photocurrent were determined by thermal activation of carriers across the energy band gap, with an activation energy depending either on the applied voltage or on illumination. At temperatures lower than 200 K, the rate of current variation with temperature was smaller as transport was realized by carrier hopping, via phonons, between trapping states within the energy band gap, located near in energy and around the Fermi level. However, at the same temperature range, photocurrent was independent of temperature, as it was determined by carrier hopping from higher energy states to progressively lower ones. From this analysis, carrier concentration, an effective carrier mobility and trap density were extracted. © 2013 American Institute of Physics.