Nonlinear diffusion in multilayered semiconductor systems

Using quantitative chemical mapping, we study the low-temperature interdiffusion of HgCdTe/CdTe multilayers, sampling volumes 14 orders of magnitude smaller than previously needed for such measurements. Our results show interdiffusion to be strongly depth dependent and nonlinear, and allow the direct determination of thermodynamic parameters of interest at individual interfaces. The high spatial resolution of our technique establishes that the stability of a layer can depend sensitively on its depth from the surface.