Optoelectronic on-chip characterization of ultrafast electric devices: Measurement techniques and applications

A comprehensive description of a modular optoelectronic measurement system for the characterization of high-frequency microelectronic devices and circuits is presented. Depending on application, specific techniques to generate, synchronize to, and detect high-frequency electric signals are combined covering a frequency range of more than three orders of magnitudes from 2 to 4000 GHz. We discuss on-chip electric-pulse generation by freely positionable photoconductive probes and by direct optical excitation of active devices. Alternatively, for measurements with external, electronically generated signals, the system is laid out to lock onto periodic signals of arbitrary frequency employed as clock signal for the circuit under test. With respect to detection, the following approaches are discussed: sampling with freely positionable electrooptic and photoconductive probe tips, and truly (probe-tip-free) all-optical testing based on the field-dependent optical nonlinearity of the circuit's substrate material. The probes are characterized concerning time resolution, linearity, sensitivity, and invasiveness. We demonstrate with a number of examples that the combination of the various modules allows one to optimize the approach to a specific testing problem. Measurements of the linear and nonlinear behavior of active and passive devices as well as circuits are presented. The electric field, respectively potential, is measured locally (point measurements) or in its spatial distribution (field mapping) both in the near and far field.