Charge Density in Atmospheric Pressure Chemical Vapor Deposition TiO[sub 2] on SiO[sub 2]-Passivated Silicon

The charge density of a film deposited on a -passivated silicon wafer is determined. The is deposited by atmospheric pressure chemical vapor deposition at , and the is grown thermally at . This stack is a useful coating for the front surface of a silicon solar cell, as it has a high optical transmission and a low density of interface states at the interface. While these properties are beneficial to high efficiency solar cells, so too is a large charge density, as what occurs in and stacks. The and charge density of -coated and -passivated silicon are evaluated by capacitance–voltage and Kelvin probe measurements. The charge density of the is within the conservative limits of −8.5 and after deposition and of −10 and after a subsequent oxygen anneal. Photoconductance measurements suggest that the dangling-bond defects at the interface are predominantly donorlike and, hence, that the change density in the is closer to the upper limits (less negative); this charge is too small to benefit solar cells.