We report on the measurement of oscillation frequency and spectral linewidth of sub-terahertz GaInAs/AlAs resonant tunneling diode (RTD) oscillators by harmonic heterodyne detection using a Ni–InP Schottky barrier diode integrated with a bow-tie antenna. For an RTD oscillating at 550 GHz and having an output power ≤1 µW, the measured spectral linewidth was at most 10 MHz; this value is in consistent with that obtained theoretically. A narrow linewidth is expected for a device having high output power and Q-factor. We also accurately measured the frequency change with changing bias voltage for the RTD oscillator; this result is useful for frequency modulation and can be applied to the phase-locked loop system.
The effects of Pr 3þ substitution on electrical properties of Bi(Fe 0:95 Mn 0:05 )O 3 (BFMO) thin films are investigated. The leakage current densities of BFMO films can be significantly suppressed by Pr 3þ substitution. Dielectric analysis reveals that dielectric constants of the films increase with increasing Pr 3þ content. Reduced loss tangents are obtained in Pr 3þ -substituted BFMO films. Ferroelectric measurements demonstrate that Pr 3þ substitution is helpful for lowering the coercive fields of films. In addition, a double hysteresis loop is observed in the BFMO film with 25% Bi 3þ substituted by Pr 3þ . This may be ascribed to the existence of the defect-complexes. #
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