Self-Heating Effect in a 65 nm MOSFET at Cryogenic Temperatures

We characterized the thermal behavior of a 65 nm bulk CMOS transistor, by measuring the self-heating effect (SHE) as a function of bias condition. We demonstrated that at a base temperature of 6.5 K the channel temperature of the transistor can increase up to several tens of kelvins due to power dissipation. The thermal behavior of the transistor is determined not only by the thermal response of the transistor itself but also by the thermal properties of the surroundings, i.e., source, drain, bulk, and gate interfaces, metal contacts, and vias. On top of it, the thermal response is bias-dependent through bias dependence of power and self-heating. This information becomes relevant for proper design of integrated circuits for quantum computing or other cryogenic applications, where the circuitry requires to be operated at a stable cryogenic temperature

Superconducting Integrated Terahertz Spectrometers

A superconducting integrated receiver (SIR) comprises all of the elements needed for heterodyne detection on a single chip. Light weight and low power consumption combined with nearly quantum-limited sensitivity and a wide tuning range of the superconducting local oscillator make the SIR a perfect candidate for many practical applications. For the first time, we demonstrated the capabilities of the SIR technology for remote operation under harsh environmental conditions and for heterodyne spectroscopy at atmospheric limb sounding on board a high-altitude balloon. Recently, the SIR was successfully implemented for the first spectral measurements of THz radiation emitted from intrinsic Josephson junction stacks (BSCCO mesa) at frequencies up to 750 GHz; linewidth below 10 MHz has been recorded in the high bias regime. The phase-locked SIR has been used for the locking of the BSCCO oscillator under the test. To extend the operation range of the SIR well above 1 THz, a new technique for fabrication of high-quality SIS tunnel junctions with gap voltage Vg up to 5.3 mV has been developed. Integration of a superconducting high-harmonic phase detector with a cryogenic oscillator opens a possibility for efficient phase locking of the sources with free-running linewidth up to 30 MHz that is important both for BSCCO mesa and NbN/MgO/NbN oscillators