Theory of a tunnel diode oscillator in a microwave structure

The properties of point-contact Josephson junctions operated as mixers with an external local oscillator at 130 GHz have been studied, and the results compared with predictions of the resistively shunted junction model. It was found that the junction’s output noise could be within a factor of 1.5 of the model prediction based on the thermal-driving noise. When the coupling to the rf source was optimized, a factor of 2 discrepancy was typical. The measured conversion efficiency agreed with the model, within the experimental uncertainty in the equivalent microwave circuit. The best coupling was achieved in full-height waveguide. The best overall performance, measured using the hot/cold source technique, was a single sideband conversion efficiency of 0.30 and a mixer-noise temperature of 180 K (both ±20%). The best junctions were made of Nb, with carefully prepared points. Nonideal behavior in other junctions is ascribed to heating effects. There is some evidence that junctions whose resistance exceeds a threshold value of ∼60 Ω are no longer well described by the RSJ model. A discussion is given of possible improvements in performance with better junctions or improved rf matching.

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Homogeneous molybdenum disulfide tunnel diode formed via chemical doping

Liu

Choi

et al. 2018

Applied Physics Letters

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We report on a simple, controllable chemical doping method to fabricate a lateral homogeneous MoS2 tunnel diode. MoS2 was doped to degenerate n- (1.6 × 1013 cm−2) and p-type (1.1 × 1013 cm−2) by benzyl viologen and AuCl3, respectively. The n- and p-doping can be patterned on the same MoS2 flake, and the high doping concentration can be maintained by Al2O3 masking together with vacuum annealing. A forward rectifying p-n diode and a band-to-band tunneling induced backward rectifying diode were realized by modulating the doping concentration of both the n- and p-sides. Our approach is a universal stratagem to fabricate diverse 2D homogeneous diodes with various functions.

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Theory of a tunnel diode oscillator in a microwave structure

Cited by 20 publications

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Tunnel Diode Devices

Tunnel Diode Devices

Point-contact Josephson mixers at 130 GHz

Homogeneous molybdenum disulfide tunnel diode formed via chemical doping

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