In the 20^th century, microelectronics was revolutionized by silicon—its semiconducting properties finally made it possible to reduce the size of electronic components to a few nanometers. The ability to control the semiconducting properties of Si on the nanometer scale promises a breakthrough in the development of Si-based technologies. In this paper, we present the results of our experimental studies of the photovoltaic effect in Ag₂S QD/Si heterostructures in the short-wave infrared range. At room temperature, the Ag₂S/Si heterostructures offer a noise-equivalent power of 1.1 × 10⁻¹⁰ W/√Hz. The spectral analysis of the photoresponse of the Ag₂S/Si heterostructures has made it possible to identify two main mechanisms behind it: the absorption of IR radiation by defects in the crystalline structure of the Ag₂S QDs or by quantum QD-induced surface states in Si. This study has demonstrated an effective and low-cost way to create a sensitive room temperature SWIR photodetector which would be compatible with the Si complementary metal oxide semiconductor technology.

The study of the origin and transport of water in the universe is an important part of the scientific program of the Millimetron space observatory. This will be made possible by observations conducted in single-dish mode using an onboard instrument - the High Resolution Spectrometer (HRS). This instrument incorporates heterodyne array receivers operating within the range $0.5 -2.7$ THz, comprising 3-pixel arrays of superconductor-insulator-superconductor (SIS) mixers operating at frequencies below 1.3 THz and 7-pixel matrix receivers based on NbN HEB mixers observing above 1.3 THz. This paper presents the current status of development for a mixers planned for use in the HRS instrument of the Millimetron space observatory.

We present an analysis of a waveguide structure for a 211-275 GHz Sideband Separating (2SB) mixer based on SIS tunnel junctions. A general analytical model describing a quality of Sideband Rejection Ratio (SRR) is developed. It shows a crucial influence of reflections from single-ended mixers, RF load and the RF hybrid on the SRR level. Due to intrinsic asymmetry of 2SB waveguide structure, the reflections strongly affect both the balance of the observed signal and the balance on the LO pumping signal. The model is verified and confirmed by 3D electromagnetic simulations showing good qualitative and quantitative agreement. The developed theory gives a practical tool to design 2SB waveguide mixers with a required SRR level. Based on the presented theory, the waveguide structure of the 211-275 GHz 2SB SIS mixer is designed. It is predicted a degradation of SRR level from 26 dB to about 18 dB due to reflections. The developed model explains some experimental data measured for 2SB SIS mixers developed earlier.

The microwave properties of the components of the waveguide structure of a heterodyne receiver in the range 211–275 GHz with sideband separation based on a pair of superconductor–insulator–superconductor (SIS) tunnel junctions are described. The following elements of the waveguide structure have been studied: a hybrid four-port splitter, a directional coupler, a T-shaped splitter, and a waveguide absorber. S parameters for all elements are calculated. For the hybrid divider, the phase balance is additionally shown, which has deviations of less than 0.4 deg, and the amplitude balance is within 1 dB. The expected level of quality of band separation in a receiver with band separation when using the studied waveguide elements is analyzed, its value is more than –25 dB. Waveguide elements are designed taking into account that the block will be manufactured by precision milling; the minimum dimensions of the waveguide structure are limited by the diameter of the cutter used; in our case, 100 µm was chosen. All numerical calculations were performed by the finite interval method in the HFSS package.

The microwave properties of the components of the waveguide structure of a heterodyne receiver in the 211...275 GHz range with sideband separation based on a pair of superconductor–insulator–superconductor (SIS) tunnel junctions are described. The following elements of the waveguide were studied structures: hybrid four-port splitter, directional coupler, T-shaped splitter body and waveguide absorber. S parameters were calculated for all elements. For hybrid divider additionally shows a phase balance with deviations of less than 0.4 degrees, and an amplitude balance within 1 dB. The expected level of quality of band separation in a band separation receiver using the studied waveguide elements is analyzed; its value is more than –25 dB. The waveguide elements are designed taking into account the fact that the block will be manufactured using precision milling; the minimum dimensions of the waveguide structure are limited by the diameter of the cutter used; in our case, 100 μm was chosen. All numerical calculations were performed using the finite interval method in the HFSS package.