Capacitance-voltage characteristics of grain boundaries in cast polycrystalline silicon

This paper reports capacitance-voltage measurements of grain boundaries made on cast polycrystalline silicon wafers. It has been observed that unlike the case of symmetric grain boundaries, the capacitance-voltage characteristics measured at high frequency, depend upon the polarity of the applied dc voltage. This deviation has been attributed to the difference in conductivities in the grains forming the grain boundary. Based on this, capacitance-voltage characteristics of grain boundaries have been calculated. Carrier trapping and emission by the grain boundary states have been considered to calculate the change in the filled trap state density due to the applied bias. A monoenergetic trap level has been assumed. The computed capacitance-voltage curves justify the observed variations