This month examination of carrier lifetime was performed. In addition I have changed the type of base material (monocrystalline silicon) and the way of surface passivation. For these measurements chemical passivation of silicon in 0.07M QM was used. Such treatment passivates the surface after 20 minutes and keep it secure for about one hour.
In addition, I took up spots on the silicon surface after alkaline texturization. Not using bleach but long soak get rid them. Recipe of silicon cleaning using in electronics worked well.