First Attempt to Develop an On-Chip Double-Shielded QHR Device for Use in AC Measurements

With the aim of enhancing the performance of ac quantized Hall resistance (QHR) measurements, an on-chip double-shielded (OCDS) QHR device and a DS chip carrier have been fabricated at the National Metrology Institute of Japan and have been studied with ac at the Physikalisch-Technische Bundesanstalt. The device has been developed on a GaAs/AlGaAs heterosubstrate using a technique to improve the yield ratio of the contact resistance and to form a high-quality insulation layer. The chip carriers have been fabricated to be compatible with the EURAMET ac QHR chip carriers. The fabricated OCDS QHR devices have been evaluated with dc and confirmed to satisfy the Revised technical guidelines for reliable dc measurements of the quantized Hall resistance. Results of the ac measurements for the devices on the dedicated chip carriers show that the shape of the i = 2 plateau at zero shield potential is not flat, and the linear frequency dependence of the QHR amounts to around -0.15 μΩ/Ω)/kHz. Improved shield designs are proposed to reduce the frequency dependence.