Gallium arsenide probes for scanning near-field probe microscopy

Gallium arsenide is introduced as a material for the fabrication of novel probes for scanning probe microscopy (SPM). Compared to conventional probe materials (silicon, silicon nitride), III/V semiconductors such as gallium arsenide offer exceptional material properties: a direct band gap appropriate for the fabrication of optical sensors, high electron mobility necessary for high-frequency devices, and high electrical resistance exploited to reduce electrical losses in microwave guide applications. We report on novel developments in the field of gallium arsenide cantilevers with integrated tips for SPM applications. As a result of an intensive study of the gallium arsenide etching behavior we are able to adapt the tip shape to the requirements in SPM, for example, high aspect ratio, minimized radius of curvature, and low surface roughness. These cantilevers represent the basic sensor design for both, passive as well as active scanning near-field probes. As a first approach, for an active SPM probe a Schottky diode integrated in the tip apex was produced. First results an the thermal and optical characterization of Schottky diode probes are presented. High-frequency measurements of a coplanar microwave guide made of semi-insulating GaAs in comparison to silicon were carried out. Additionally, concepts for a light-emitting diode and a laser diode integrated in a tip a challenge for future concepts in SNOM - are discussed.