Transfer-Substrate Process for InP RTD-Oscillator Characterization

THz oscillators with on-chip antennas containing no ground plane are affected by substrate modes and therefore undirected radiation into free space. When integrating such antennas with focusing lenses, accurate sub-mu m alignment is required. This work presents an assembly process utilizing an HRFZ-Si transfer substrate between the InP RTD chip and a hyper-hemispherical silicon lens, enabling precise alignment. We developed a bonding process for 1.2 x 1.2 mm(2) InP RTD chips with an optical adhesive utilizing an advanced sub-micron bonder. THz-TDS measurements of the HRFZ silicon wafer were carried out to analyze the losses within the created setup by EM simulations. The assembly process was verified with measurements of a 300 GHz triple barrier (TB)-RTD oscillator using an SBD detector.

Automated summary

This paper presents an assembly process using HRFZ-Si transfer substrate for precise alignment of THz oscillators with hyper-hemispherical silicon lenses. The bonding process and THz-TDS measurements were conducted to analyze the losses within the setup, and the process was verified with experiments on a 300 GHz triple barrier (TB)-RTD oscillator.