Reliability investigations on LTG-GaAs photomixers for THz generation based on optical heterodyning

Abstract

Optical heterodyne conversion, or photomixing, is a frequency-agile technique that generates continuous-wave radiation at THz frequencies using thin films of low-temperature-grown (LTG) GaAs at high electrical bias. Very high electric fields (>300 kV/cm) and thermal excitation by focused laser illumination require reliability assessments prior to implementation in THz systems. Pulsed electrical stress and DC measurements under optical illumination are used to characterise the reliability of photomixers for THz generation based on optical heterodyning. An improvement in terms of reliability is observed by replacing Ti/Au by Pt metallisation.