Observation of multiple high-field domains in n-GaAs

Multiple high-field domains have been observed in n-GaAs using a resistive point-contact probe having a 2-micron spatial resolution and a 5-GHz frequency response. The probe is easy to construct, is compact and maneuverable, and can be used for identifying oscillatory modes when n-GaAs or other bulk semiconductors are embedded in coaxial or waveguide microwave circuits.