The Optical Gain of a Si-Based Lattice-Matched Si0.15Ge0.621Sn0.229/Si0.637Ge0.018Sn0.345 MQW Laser

Abstract

We study the optical-gain characteristics of a Si-based MQW laser, in which the active region has 20 Si_0.15Ge_0.621Sn_0.229 quantum wells separated by 20 Si_0.637Ge_0.018Sn_0.345 barriers. We reach a maximum optical gain of 2300 cm⁻¹ with an estimated carrier concentration of 5·10¹⁸ cm⁻³, which is equivalent to the transparent current density equal to 0.5 kA/cm². Furthermore, we discuss the optical confinement factor and modal gain. The modal gain depends sensitively on the number of the quantum wells (QWs), and this fact restricts the optical confinement factor. The modal gain of the model we proposed can reach 1500 cm⁻¹ at the injection current density equal to 3 kA/cm². We hope that our results show the possibility to obtain a Si-based near-infrared laser.