INSTABILITY-DRIVEN PHASE SEPARATION FOR QUANTUM STRUCTURE FORMATION IN III-V SEMICONDUCTORS

High temperature phase instability limits the performance of III-V zinc blende semiconductor devices. A technique using an encapsulant and sacrificial layer is developed to reduce thermal degradation by group V sublimation during thermal processing of InGaAs/GaAs structures. This technique is successful in preventing As sublimation and preserving an atomically smooth surface required for surface-sensitive characterization. The degradation of the GaAsSb/InP interface by phase separation is studied. Significant interdiffusion and intermixing occurs due to the formation of a molten InSb at the interface. The intermixing is driven by phase separation and melting of the InSb interfacial layer that enhances atomic mobility. Externally applied stress by SiNx is used to adjust the strain within the GaAsSb epilayer from compressive to tensile during high-temperature annealing. A critical biaxial strain appears to exist that strongly affects the morphology of the phase separated regions, while slowing down the degradation kinetics.