A bow-tie photoconductive antenna using a low-temperature-grown GaAs thin-film on a silicon substrate for terahertz wave generation and detection

Abstract

This paper presents heterogeneously integrated bow-tie emitter–detector photoconductive antennas (PCAs) based on low-temperature grown-gallium arsenide (LTG-GaAs) thin-film devices on silicon-dioxide/silicon (SiO2/Si) host substrates for integrated terahertz (THz) systems. The LTG-GaAs thin-film devices are fabricated with standard photolithography and thermal evaporation of metal-contact layers of chromium (Cr), nickel (Ni) and gold (Au). They are etched selectively and separated from their growth GaAs substrate. The LTG-GaAs thin-film devices are then heterogeneously integrated on bow-tie antenna electrodes patterned on the surface of a SiO2/Si host substrate for THz emitters and THz detectors. Cost-effective and selective integration of LTG-GaAs thin-film devices on a Si platform is demonstrated. THz radiation from the fabricated THz PCAs is successfully measured using a pump–probe THz time-domain configuration. The THz temporal duration was measured at full width half maximum of 0.36 ps. Its frequency spectrum exhibits a broadband response with a peak resonant frequency of about 0.31 THz. The demonstration illustrates the feasibility of creating heterogeneously integrated THz systems using separately optimized LTG-GaAs devices and Si based electronics.

Demonstration of a terahertz coplanar-strip spoof-surface-plasmon-polariton low-pass filter

“…These components were fabricated using a multi-step process involving photolithography, gold (Au) sputtering, and wet-etching. The process is detailed in other works 32 , but we summarize it here for completeness. The desired LT-GaAs layer is grown on a sacrificial AlAs layer on a semi-insulating GaAs substrate.…”

Photoconductive emitters for pulsed terahertz generation

“…Further work by Awad et al [101] and later by Rios et al [98,106] both revealed how this bonding technique can be used to construct PCA array features. In the latter of these, 2 µm thick LT-GaAs is removed from its SI-GaAs growth substrate and bonded with SiO 2 -on-Si [106].…”

“…It can then undergo epitaxial liftoff (ELO) from its growth substrate and van der Waals forces can be used to bond the LT-GaAs film, typically 0.5-3 µm thick, to a new host substrate. This technique has been shown to work with various materials including Si [98], glass [99,100], sapphire [99][100][101], quartz [102], LiNbO 3 , InP, and diamond [103]. In the early works of Heiliger et al [99,100], 0.5 µm thick LT-GaAs films were transferred onto both sapphire and glass substrates.…”

Demonstration of a Terahertz Coplanar-Strip Spoof-Surface-Plasmon Polariton Low Pass Filter

“…These components were fabricated using a multi-step process involving photolithography, gold (Au) sputtering, and wet-etching. The process is detailed in other works 28 , but we summarize it here for completeness. The desired LT-GaAs layer is grown on a sacrificial AlAs layer on a semi-insulating GaAs substrate.…”