ION-BEAM INTERMIXING OF SEMICONDUCTOR HETEROSTRUCTURES FOR OPTOELECTRONIC APPLICATIONS

The ability of radiation enhanced quantum well (QW) intermixing to pro duce active integrated photonic devices has been demonstrated by the m anufacture of a set of wavelength tuned lasers from a single semicondu ctor wafer, Defects, created in the InP-based structure by a high ener gy (1 MeV)P implant, enhance the diffusion of atomic species across th e as-grown heterojunctions during subsequent rapid thermal annealing ( 90 s at 700 degrees C). As a result, the QW band gap energy is blue sh ifted with respect to unirradiated regions. It is shown that by implan ting through a SiO2 mask of varying thickness, the bandgap of the QW c an be selectively tailored across the wafer, Additional results from G aAs- and SiGe-based QW systems are presented to illustrate how bandgap engineering techniques may be improved through a better understanding of the defect interactions involved. In the GaAs-based structure, def ect trapping at structural interfaces has been identified as a possibl e hindrance to ion assisted intermixing. In contrast, data from the gr oup IV QWs highlights the benefits of a low temperature (24 h at 630 d egrees C) anneal prior to irradiation. By removing defects from the as -grown material with pre-annealing, the relative bandgap shift induced by ion bombardment is doubled.