The paper gives an overview of Semiconductor-based THz sources and receivers.

Efficient and compact frequency converters are essential for frequency stabilization of terahertz sources. In this paper, we present a 3.5-THz, x6-harmonic, integrated Schottky diode mixer operating at room temperature. The designed frequency converter is based on a single-ended, planar Schottky diode with a sub-micron anode contact area defined on a suspended 2-um ultra-thin GaAs substrate. The dc-grounded anode pad was combined with the radio frequency E-plane probe, which resulted in an electrically compact circuit. At 200 MHz intermediate frequency, a mixer conversion loss of about 59 dB is measured resulting in a 40 dB signal-to-noise ratio in a phase-locking application. Using a quasi-static diode model combined with electromagnetic simulations, good agreement with the measured results was obtained. Harmonic frequency converters without the need of cryogenic cooling will help in the realization of highly sensitive space and air-borne heterodyne receivers.

The DNA molecules are stable but easily fragmented by ionization radiation, which challenges DNA integrity in searching for evidence for extraterrestrial life on icy satellites. The objective was to estimate the highest value of the attenuation effect of freezing temperature on the efficacy of gamma-radiation in fragmenting dsDNA. A bacterial 16S rRNA gene inserted in a vector as a lyophilized crude cell lysate was irradiated (60Co) under the liquid nitrogen conditions (-195.8oC). The outcome was tested in a specific PCR, generating the MAIN (~600bp) as well as EXTRA “mis-primed” small-sized (~70bp) amplicons. At the ambient temperature, the main PCR product entirely disappeared upon the doze 7.5kGy while at -195.8oC, it withstood ~750kGy (~100 times difference). Vise-verse, the EXTRA short amplicon reached the maximum outcome at the dose ~400kGy and continued to persist until the tested dose 840kGy. By extrapolation, the given product could be generated upon irradiating target DNA at a dose of more than 1mGy. Such a find opens a chance (and time window of more than 25 years) to pick up freshly flushed out sub-ice-ocean microbes/DNA and get frozen as inclusions in water matrices on the Jovian Europa to verify the extraterrestrial life.