Optimizing the concentration profile of Zn with ruthenium doped InP

We have examined the diffusion of zinc (Zn) into ruthenium-doped indium phosphide (Ru-InP), which is used as the current blocking layer in buried heterostructure (BH) lasers. By applying a p-InP (Zn-doped InP)/Ru-InP/p-InP structure to the blocking layers of BH lasers, excellent laser characteristics can be obtained. Several epitaxial techniques have been used to suppress the degradation of the current blocking layers containing Ru-InP. In particular, Zn diffusion into Ru-InP in the p-InP/Ru-InP/p-InP structure is considered a main factor to cause the degradation of BH laser characteristics. In this paper, we have investigated the diffusion behavior of Zn into Ru-InP from p-InP when the p-InP/Ru-InP/p-InP structure grown by metal-organic vapor phase epitaxy is subsequently annealed. We identified suitable epitaxial growth conditions to suppress the Zn diffusion in the BH laser fabrication.