The design and simulation of p-type Si/SiGe Terahertz quantum cascade lasers

•This paper gives a new design for Si/SiGe Terahertz quantum cascade lasers.•The upper state lifetime is prolonged to 32 ps compared to previous work of 23 ps.•The optical gain is similar to the BTC structure but simple for material growth.•This paper is organized clearly, giving a fundamental demonstration of our design.

To prolong upper state lifetime in p-type Si/Si1−xGex Terahertz quantum cascade lasers, a new active region is designed in this work. Using 6×6 k·p theory, the eigenvalues and wavefunctions of heavy holes and light holes are firstly calculated in a single SiGe quantum well. The design in the active region of this THz Si/Si1−xGex quantum cascade lasers is then investigated. This work presents a SiGe quantum cascade laser with about 6.84 THz emission in the diagonal transition. The calculations show that about 32 ps of the upper state lifetime and about 9 cm−1 of optical gain are obtained, which are enhanced when compared to previous designs.