Sub-THz radiation room temperature sensitivity of long-channel silicon field effect transistors

Room temperature operating n-MOSFETs (n-type metal-oxide silicon field effect transistors) used for registration of sub-THz (sub-terahertz) radiation in the frequency range ν = 53−145 GHz are considered. n-MOSFETs were manufactured by 1-μm Si CMOS technology applied to epitaxial Si-layers (d ≈15 μm) deposited on thick Si substrates (d = 640 μm). It was shown that for transistors with the channel width to length ratio W/L = 20/3 μm without any special antennas used for radiation input, the noise equivalent power (NEP) for radiation frequency ν ≈76 GHz can reach NEP ∼6×10⁻¹⁰ W/Hz^1/2. With estimated frequency dependent antenna effective area S_est for contact wires considered as antennas, the estimated possible noise equivalent power NEP_pos for n-MOSFET structures themselves can be from ∼15 to ∼10³ times better in the specral range of ν ∼55–78 GHz reaching NEP_pos ≈10⁻¹² W/Hz^1/2.