THz

**THz Semiconductor Devices** is **semiconductor-based components generating, detecting, modulating terahertz radiation (0.1-10 THz), enabling imaging, sensing, and communication applications** — THz bridges electronics and photonics. **THz Band** 0.1-10 THz corresponds to wavelengths 30-3000 micrometers. Between microwave and infrared. **Generation** quantum cascade lasers (QCLs), resonant tunneling diodes (RTDs), photomixers generate THz. **Detection** Schottky diodes, bolometers, superconducting microbolometers detect THz. High sensitivity. **RTD Oscillators** resonant tunneling diodes oscillate due to negative differential resistance. Compact THz sources. **Frequency Tuning** bias voltage tunes RTD oscillation frequency. **QCL (Quantum Cascade Laser)** nested quantum wells; electrons cascade, emitting THz photons. Coherent THz source. **Modulation** electro-optic modulators change THz beam intensity. **Waveguides** metal or plastic waveguides guide THz. Planar antennas couple to free space. **Antennas** log-periodic, dipole, horn antennas for THz radiation. **Imaging** THz imaging penetrates many materials (textiles, paper, cardboard). Non-ionizing. Security applications (screening). **Sensing** THz spectroscopy identifies materials (absorption fingerprints). Drug identification, explosives detection. **Communication** THz wireless communication high bandwidth. Limited range (absorption in atmosphere). **Heterodyne Detection** downconvert THz to lower frequency for sensitive detection. **Schottky Mixers** Schottky diodes mix signal and local oscillator. **Noise Figure** THz detectors have high noise figure (limited by quantum noise). **Cooling Requirements** some THz devices require cryogenic cooling (QCLs, bolometers). **Room Temperature** RTDs, photomixers operate room temperature. **Integration** on-chip THz circuits combining sources, modulators, antennas. Silicon photonics + electronics. **Fabrication** semiconductor processes (GaAs, InP, silicon) compatible. **Bandwidth** THz devices inherently broadband. **Semiconductor THz devices enable applications** from imaging to communication.