Variable-temperature ultrahigh vacuum scanning tunneling microscope: Mechanical and electronic instrumentation

A variable-temperature ultrahigh vacuum scanning tunneling microscope is described which was specifically designed for the study of Ga surfaces close to the bulk melting point (Tm=29.8°C). Since the temperature must be controlled with great accuracy the sample stage and the rest of the microscope are in thermal equilibrium. The instrument also incorporates a novel approach to vibration isolation that is based on a lossy acoustic waveguide. Analog electronics form an integral part of the microscope since a dynamic range of 120 dB must be reached. Interconnection techniques are discussed in this context and a circuit of a high-voltage amplifier is shown that provides a voltage swing of ±400 V with less than 1 mVpp noise over a bandwidth of 10 kHz. Results are presented which confirm the design concepts applied to this instrument.