Determination of Positive Mobile Ion Density in Silicon Dioxide by Hydrogenated Amorphous Silicon Field Effect Technique

Abstract

It is shown that changes in the current‐voltage characteristics of a structure composed of amorphous Si:H, , and crystalline Si layers provide a powerful tool for the observation of the positive mobile ion density in the silicon dioxide. The source‐drain current in the amorphous silicon has been measured as a function of gate voltage and time. At high positive gate voltages the current increases with time because the positive mobile ions in the silicon dioxide move to the interface between amorphous silicon and silicon dioxide. Their transport through the oxide is studied as a function of time and applied voltage. The positive ion density near the interface can be determined from the electron density induced in the amorphous silicon layer by the gate voltage. The area density of positive mobile ions in a 2 μm thick thermally wet‐grown silicon dioxide has been observed to be about .