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 stu dy systematically the changes in the charge-carrier concentration of a semiconductor surface region caused by exposure to plasma during a pl asma-enhanced chemical vapor deposition process. Using this technique, the reduction in the near-surface carrier concentration as well as th e depth of carrier-density modification on n-GaAs samples have been me asured 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 i nto direct contact with the semiconductor during the deposition, the e ffect of ion-bombardment near the semiconductor surface can be reduced significantly