Abstract
Electron cyclotron resonance (ECR) plasma etch processes with 
have been investigated on different III–V semiconductor materials (
, 
, 
, and 
). The passivation depth as a function of the 
carrier concentration and the recovery upon annealing at different temperatures have been determined by C‐V measurements. Little degradation on the characteristics of Schottky diodes is observed with increasing process biases. If the 
top layer of an 
heterostructure is removed by plasma processing the Hall mobility is restored to 74% after annealing at 425°C. This is compared to a wet chemically etched reference sample. The 2‐DEG sheet density fully recovers. However, if an Si δ‐doped layer is incorporated in the heterostructure the Hall mobility and the sheet density completely restore after plasma etching and subsequent annealing. In the experiments minimal damage is observed at a substrate bias of −40 V. The direct current and high frequency characteristics of a dry and wet etched pseudomorphic heterostructure field‐effect transistors are compared.