Epitaxial Lateral Overgrowth of Indium Phosphide and Its Application in Heteroepitaxy

Sammanfattning: Monolithic integration of optoelectronics on silicon is adream. This thesis deals with the studies on the heteroepitaxyof indium phosphide on silicon substrate towards making thatdream come true. Materials growth issues, characterization anddefect identification are addressed.Epitaxial lateral overgrowth (ELOG) technique is used togrow high quality epitaxial indium phosphide on a siliconsubstrate provided with a low quality indium phosphide seedlayer. Hydride vapor phase epitaxy is used for ELOG. The growthparameters were optimized first by carrying out ELOGexperiments on an InP substrate. The lateral growth rate isstrongly dependent on the orientation of the openings,thehighest growth rate being for the openings oriented at 30ºand 60º off [110]directions. But the vertical growth rateis relatively unaffected by the opening orientation. Theobservation of an inhomogeneous and orientation dependentdopant distribution within the same layer has been explained byinvoking the bonding configurations exposed to theincorporating dopant atoms in the different emergingplanes.When ELOG of InP is conducted on InP/Si, unlike that on InPsubstrates, the lateral growth is not symmetric on both sidesdue to the propagation of defects from the seed layer. Forexample, a higher concentration of threading dislocationsintersecting the surface of the {111}A emerging planes wouldcause a higher growth rate of these planes. The growth rate of{111}A planes with respect to the others can also be caused bythe vapor phase supersaturation as predicated byBurton-Cabrera-Frank model. The determined dislocation densityin the ELOG InP on InP/Si is ~ 4X107cm-2, which is nearly two magnitude lower than in theseed layer (~ 4X109cm-2). If the seed layer is of a better quality, theELOG layer will also be. Combination of high resolution x-raydiffraction reciprocal lattice mapping and low temperaturephotoluminescence indicates that the ELOG InP layer with highaspect ratio is nearly strain-free.When ELOG of sulfur doped InP is conducted on ring shapedopenings on InP/Si substrate instead of stripe openings,octahedral shaped ELOG InP templates with smooth surface areformed. Strain compensated InGaAsP 6 periods multi-quantumwells (MQW) at 1.5 ?m wavelength (target value) were grownon these templates by metalorganic vapor phase epitaxy. RT-PLis indicative of a good quality ELOG layers. Optimized ELOG onring openings may become very attractive for heteroepitaxy ofIII-V compounds on silicon.As an extension of ELOG of InP on InP/Si, growth of InP isalso conducted on planar Focused-Ion-Beam (FIB)-modified (001)GaAs substrate. The impacts of the III/V ratio,crystallographic orientation of implanted lines andimplantation dose were explored. The choice of suitable growthconditions makes it possible to obtain continuous InP wiresaligned in all possible directions.