Dopant diffusion and current-voltage studies on epitaxial InP codoped with Ru and Fe
Semi-insulating Fe and Ru codoped InP epitaxial layers grown by low-pressure hydride vapor phase epitaxy have been investigated. InP∶Ru and InP∶Fe, Ru layers were grown on p-InP∶Zn andn-InP∶S, substrates, in order to study dopant diffusion and electrical characteristics. Dopant diffusion profiles of Ru, Fe and Zn were measured by secondary ion mass spectroscopy. A small but noteworthy diffusion front is observed when InP∶Ru is adjacent to InP∶Zn, but not when adjacent to n-InP. For InP∶Fe codoped with Ru a pronounced interdiffusion of Fe and Zn is observed for Ru concentrations less than 2 1017 cm−3, but for a higher Ru concentration the interdiffusion is clearly suppressed. Moreover, when InP is codoped with Fe and Ru, the small diffusion tail of Ru in InP∶Zn vanishes. Unlike InP∶Fe, resistivities above 1 108 cm are measured for both electron and hole-current injection in InP∶Fe,Ru.