Simulated properties of printed antennas on silicon substrates for THz/sub-THz arrays

Some properties of printed antennas and arrays for uncooled silicon plasmon detector arrays based on field effect transistors are shortly discussed. Antenna geometry has been optimised for maximising gain at 300 GHz. It is shown that for bow-tie antennas in the arrays in diffraction limit approximation, there are almost no cross-talks between the neighbour antennas. It is shown that the gain for one antenna is higher than that for antenna, in the array

Intrinsic concentration dependences in the HgCdTe quantum well in the range of the insulator-semimetal topological transition

The band structure and dependences of the intrinsic concentration in the mercury-cadmium-telluride (MCT) Hg₀.₃₂Cd₀.₆₈Te/Hg₀ Cd₀ Te/Hg₀.₃₂Cd₀.₆₈Te quantum wells in the framework of the 8x8 k.p envelope function method on the well width L and composition x were calculated. Modeling of the energy spectra showed that the intrinsic concentration can vary about an order of magnitude with variation of the well width and chemical composition in the range of x < 0.16 and well width L < 20 nm at the liquid nitrogen temperature. These strong variations of the carrier concentration are caused by the insulator-semimetal topological transition

Sub-THz nonresonant detection in AlGaN/GaN heterojunction FETs

Un-cooled AlGaN/GaN-based heterojunction field-effect transistors (HFET) designed on sapphire (0001) substrates were considered as 140 GHz direct detection detectors without any specially attached antennas. The noise equivalent power (NEP) of these detectors was ~ 10⁻¹⁰ W/Hz¹/² in the observed radiation frequency range at ambient temperatures. It has been shown that the ultimate value for the AlGaN/GaN HFET detectors (in 0.25-μm technology) can reach NEPopt ≈ 6•10⁻¹² W/Hz¹/² , and it is 3-fold lower than that for Si MOSFET (in 0.35-μm technology)

Properties of CdTe thin films prepared by hot wall epitaxy

CdTe thin films were grown on different substrates: BaF₂ (111), polished Si (100), SiO₂, bulk CdTe (110) and HgxCd₁₋xTe layers by hot wall epitaxy (HWE). Chosen temperature parame-ters and technological process of thin film fabrication provided the growth rate of about 0.03 mm/min. The current-voltage characteristics and transmission spectra were measured. X-ray diffrac-tion data (XRD) measurements were carried out as well

Electron relaxation and mobility in the inverted band quantum well CdTe/Hg₁₋xCdxTe/CdTe

Electron relaxation processes at nitrogen temperatures in CdTe/Hg₁₋xCdxTe/CdTe quantum well (QW) with an inverted band structure is modelled. In this structure, scattering by longitudinal optical phonons, charged impurities, acoustic phonons and interfaces were taken into account. It was found that for undoped and lightly doped QWs (concentration of background n-type charged impurities in the well is 10¹⁴ – 10¹⁶ cm-³ or less), for x close to the band inversion value 0.16, the electron mobility grows considerably when the QW width decreases. This mobility is higher for samples with smaller concentrations of charged impurities