Free-orientation integration by direct bonding: fabrication of [001] InP-based 1.55 /spl mu/m-wavelength lasers on [110] GaAs substrate

We propose a new concept "free-orientation integration", which should be implemented by the direct bonding technique. In order to investigate the possibility of such integration, we examine the direct bonding of [001] InP and [110] GaAs. Cross-sectional observation shows that these wafers can be united without generating dislocation. [001] InP-based 1.55-/spl mu/m wavelength lasers are fabricated on [110] GaAs. The light-current characteristics of the lasers are almost identical to those of lasers fabricated on [001] GaAs, while the turn-on voltage is higher by about 0.4 V, due to the large band discontinuity at the bonding interface. The results show that device fabrication by direct bonding on different materials with different surface orientations is possible with satisfactory quality.