High quality InAs quantum dot lasers on germanium substrates

InAs/GaAs quantum dot (QD) laser structures were fabricated using gas source molecular beam epitaxy (GSMBE) on Ge (100) substrate. Low temperature grown GaAs buffer layer prevented formation of anti-phase domain (APD). Growth temperature and deposition thickness of InAs were optimized, respectively. Active region consists of five stacked InAs QD layers separated by 40 nm GaAs space layer. Ridge waveguide laser diodes with a strip with of 8 μm were fabricated. Room temperature continuous wave (RT CW) emission was achieved with lasing wavelength centred at 1.05 μm and maximum laser output power reached up to 110 mW from single facet without any facet coating. Performance of similar laser diodes on Ge and GaAs substrates was compared and the laser characteristic temperature for both devices was found similar.