FLUORINE DIFFUSION AND ACCUMULATION IN SI STEP-DOPED INALAS LAYERS

The quantitative relation between fluorine (F) accumulation and Si don or concentration in n-InAlAs layers on InP substrate was investigated for several kinds of step-doped InAlAs samples using secondary ion mas s spectroscopy. From the depth profile of F and Si donors in a periodi c i-/n-InAlAs sample, we found that F accumulates only in n-InAlAs lay ers, passing through i-InAlAs layers. We also found that the amount of F accumulation in an n-InAlAs layer depends on the Si doping concentr ation. The experimental results can be explained by considering two st ates of F. In one state, F is bound to a Si donor and immobile, and in the other it is free and can diffuse. (C) 1998 American Institute of Physics. [S0003-6951(98)01443-0].