GAAS ALGAAS LIGHT EMITTERS FABRICATED ON UNDERCUT GAAS ON SI/

Stable GaAs/AlGaAs light-emitting diodes (LEDs) on Si substrates were realized by growing device structures on undercut GaAs on Si (UCGAS) w hich reduces both thermal stress and dislocation density. The output e fficiency of the UCGAS LEDs was almost the same as that of homoepitaxi al LEDs, and maintained stable operation for 3000 h. The device degrad ation mechanism in conjunction with the residual stress and the disloc ation density was investigated, and it was found that the stress had a more significant eff ect on device degradation than the dislocation d ensity. The output efficiency and the thermal properties of the LEDs a re also analyzed. UCGAS lasers were fabricated, and both efficiency an d threshold current equal to those of homoepitaxial lasers were obtain ed.