SURFACE DAMAGE ON GAAS ETCHED USING A MULTIPOLAR ELECTRON-CYCLOTRON-RESONANCE SOURCE

Surface damage on GaAs induced by etching using an electron cyclotron resonance (ECR) source has been studied as a function of pressure, mic rowave power, sample distance from the ECR source, RF power, and gas c omposition. Damage was evaluated by measuring the current-voltage (I-V ) and capacitance-voltage (C- V) characteristics on Schottky diodes fa bricated on the etched surface. Etch-induced damage is found to depend mainly on the ion energy and the concentration of reactive species. T he diode characteristics are improved when the samples are etched at l ower pressure, higher microwave power, and closer distance to the ECR source. The diodes become more leaky and the intercept voltage extract ed from the C-V measurements increased at higher RF power, which sugge sts the formation of a heavily damaged layer at higher ion energy. It is also found that an Ar plasma introduces more damage than a N2 plasm a as observed by a higher ideality factor and a lower barrier height o n the samples etched by Ar sputtering. Addition of Cl2, as little as 1 0%, results in diode characteristics close to that of the unetched sam ple. The damage observed can be classified into major and minor degree s of damage. In this study, most of the samples have only minor damage . Major damage was observed only on samples that were etchecl at high RF power or with a low concentration of reactive species.