ELECTROCHEMICAL CAPACITANCE-VOLTAGE PROFILING - A NEW TECHNIQUE TO STUDY PLASMA DAMAGE DURING A PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION

For the first time, electrochemical C-V profiling has been used to study systematically the changes in the charge-carrier concentration of a semiconductor surface region caused by exposure to plasma during a plasma-enhanced chemical vapor deposition process. Using this technique, the reduction in the near-surface carrier concentration as well as the depth of carrier-density modification on n-GaAs samples have been measured as a function of plasma power and desposition temperature. The possible damage mechanisms also have been evaluated. Finally, we show that by using an electrical shield to prevent the plasma from coming into direct contact with the semiconductor during the deposition, the effect of ion-bombardment near the semiconductor surface can be reduced significantly