We have fabricated several low-noise direct-current superconducting quantum interference device (SQUID) magnetometers from single layers of YBa2Cu3O7−δ on 10 mm×10 mm bicrystal substrates. The magnetometer design consists of a single-turn pickup loop that is directly coupled to the SQUID inductance. At 77 K, these magnetometers exhibit large voltage modulation with applied flux of over 40 μV. The minimum flux noise, measured at 77 K using conventional flux-locked loop electronics with bias current reversal, is 3.5×10−6 Φ0/√Hz above 10 kHz and 6.5×10−6 Φ0/√Hz at 1 Hz. The field-to-flux conversion efficiency is measured to be 10 nT/Φ0, resulting in a white magnetic field noise of 35 fT/√Hz above 10 kHz, increasing to 65 fT/√Hz at 1 Hz.

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High-performance backside-illuminated photodiodes have been fabricated for the first time from InAs1−xSbx-InAs heterostructures prepared by liquid-phase-epitaxy technique. The peak wavelength can be tuned compositionally from 3.1 to over 7.0 μm at 77 K. The half-width of the spectral responses as narrow as 1760 Å (at 4.0 μm) have been achieved. Internal quantum efficiencies of 90% and zero-bias-resistance–area products of 2×107 Ω cm2 have been obtained at 77 K.