Zinc diffusion in InGaAsP

Abstract

Ampoule diffusion of Zn in undoped liquid phase epitaxial InGaAsP layers between 425 and 525°C shows the Zn solubility, as measured with secondary ion mass spectrometry, to be much larger than in InP and to be slightly less than in GaAs. The acceptor concentration, as determined by capacitance-voltage measurements, is 60%-90% of the Zn concentration. Incorporation and diffusion of Zn can be described with the interstitial-substitutional model. The difference between the acceptor and Zn concentrations can be explained by compensating Zn interstitial donors or by neutral Zn-vacancy complexes. The diffusion depth is slightly smaller than in InP and much larger than in GaAs. In n-type InGaAsP, profiles are found with a cut-off similar to the behavior in InP. The solubility is higher than in undoped InGaAsP.