Generation and amplification of confined acoustic phonons in a quantum wire via the Čerenkov effect

We study the effect of generation and amplification of confined acoustic phonons by drifting electrons in an embedded quantum wire. A general formula for the phonon amplification coefficient α has been derived. Our calculations show that the quantum wire structure can be used for electrical generation of an intense high-frequency coherent phonon flux. The amplification coefficients of the order of cm−1 can be achieved in the sub-THz range for the example of Si0.5Ge0.5 quantum wires embeded in Si.