Towards Si1−xGex quantum-well resonant-state terahertz laser

Abstract

We report on the experimental evidence for terahertz (THz) lasing of boron-doped strained Si1−xGex quantum-well structures. The lasing arises under strong electric fields (300–1500 V/cm) applied parallel to interfaces. The spectrum of THz stimulated emission is presented showing the lasing wavelength near 100 μm and the modal structure caused by a resonator. The mechanism of population inversion is based on the formation of resonant acceptor states in strained SiGe layer.

Optically pumped terahertz semiconductor bulk lasers

“…However, there is a problem in creating population inversions of charged carriers in semiconductors for the THz spaced states because of the fast phonon-assisted and Auger relaxations that usually tend to thermalize carrier distributions. New proposals for THz semiconductor oscillators are based on the intra-band optical transitions: p-Ge intra-valence band bulk lasers [1], inter-subband quantum cascade [2, 3] and fountain lasers [4] as well as SiGe strained heterostructure lasers [5]. These lasers use the fast low-temperature relaxation processes to maintain the population inversion.…”

Analytical approach to the impurity scattering in quantum wells

“…It was shown in [1][2][3] that impurity states (ISs) in quantum wells (QWs) can play a determining role in creation of so-called inverted distributions, which can lead to novel optical devices in the far-infrared (or terahertz) range [4,5]. Our studies of this topic [6,7] led us to attempt to find a rather simple and quick technique for, at least, semiquantitative estimation of the ladder of impurity binding energies.…”

Lateral drift of photo-generated charge carriers in the p-SiGe/Si heterostructures with quantum wells

“…There was reported about development of various kinds of transistors [1][2][3][4], photodetectors based on intrinsic absorption as well as based on intraband and impurity optical transitions [5][6][7][8][9], lasers for the THz range [10,11].…”