Quantum Channel HEMT

In terahertz (THz) applications, Field-effect transistors (FETs) have emerged as prime candidates for the next generation of THz and sub-THz electronics. One of the main advantages of TeraFETs over state-of-the-art commercial THz electronics based on Schottky diodes is their ability to tune the plasma frequency over a wide range via gate voltage, which adjusts the sheet carrier density (electrons or holes) in the device channel. In this paper, we demonstrate that employing a Quantum Channel (QC) design, where the back barrier is positioned in close proximity to the front barrier, resulting in a channel thickness between 1 and 10 Bohr radii, offers significant advantages for TeraFET applications. This configuration enables increasing the maximum achievable density. In electro-optics applications, the QC design provides a unique opportunity for implementing an opto-FET, where optical absorption is modulated by the gate voltage. The key advantage of the QC-HEMT is the ability to shift the absorption edge by a large energy on the order of the Fermi level by changing the sheet carrier concentration in the device channel by modulating the gate voltage and, thereby, modulating the Moss–Burstein shift, effectively altering the optical band gap sensed by incoming radiation optical radiation by an electric field. A large sheet carrier concentration achieved in QC-HEMTs allows for a much broader modulation range of plasma frequencies and facilitates frequency multiplication via nonlinear plasmonic resonance (approximately 3 times higher). A large sheet carrier concentration also facilitates frequency multiplication via nonlinear plasmonic resonance. Such nonlinear frequency rectification dramatically increasing the frequency range (up to 1 THz or even higher) at much higher achievable powers, since the power is introduced via uniform gate voltage pumping by large-area grating gate structures. For an optical QC-HEMT, a large Moss-Burstein shift makes the optical QC-HEMT design superior as an optical modulator and optical spectrometer.