Growth of patterned GeSn and GePb alloys by pulsed laser induced epitaxy

While modulators, waveguides and detectors have been successfully integrated in silicon devices, a laser source still remains a challenge. Unfortunately, in silicon and germanium, indirect band transitions are favored, making laser emission unlikely. Direct bandgap transitions have recently been demonstrated in germanium by introducing tensile strain with heavy n-type doping or by alloying with Sn. GePb alloys seem to be promising candidates here as well, since the required Pb concentration is predicted to be far lower than for Sn.