Band structures and optical gain of direct-bandgap tensile strained Ge/Ge1-X-YSiXSnY type I quantum wells

The band structures and optical gain of tensile strained Ge/GeSiSn QWs with different Sn composition are investigated by using 6-band k.p method. The band lineups of Ge/GeSiSn are given. The hole energy dispersion curves of 80 Å/200 Å Ge/GeSiSn QWs are calculated. We find that optical gain will crease and the peak position will decrease when increasing Sn composition.