50-Ω-matched system for low-temperature measurements of the time-resolved conductance of low-dimensional semiconductors

Abstract

We describe the construction of a low-temperature cryostat that may be used to study the time-dependent conductivity of low-dimensional semiconductors with time resolution of a few-hundred picoseconds. The system makes use of semirigid coaxial cables to provide the necessary connections from room-temperature instrumentation to the low-temperature stage, and features a specially designed launch that provides efficient 50 Ω impedance matching to the semiconductor system of interest. In order to explore the capabilities of the system, we perform time-resolved measurements of the magnetotransport properties of a high mobility GaAsAlGaAs two-dimensional electron gas. © 2005 American Institute of Physics.