Improved broadband on-chip time domain terahertz spectrometer for van der Waals heterostructures

Time domain THz spectroscopy is a powerful technique for studying low-energy excitations in quantum materials, but is typically restricted to samples physically larger than the electromagnetic diffraction limit (~0.3 mm). We present an on-chip THz time domain spectrometer based on transmission line-coupled photoconductive switches fabricated by aligned transfer of epitaxially grown ErAs superlattices. We benchmark our bandwidth and dynamic range, which shows significant improvement over radiation damaged silicon-based devices on silicon substrates, and anticipate the technique’s use in studying dynamics and non-equilibrium phases in exfoliable van der Waals materials and heterostructures.