The electrochemical profiling of $n^+/n$ GaAs structures for field-effect transistors

It is shown that when using a standard electrochemical profiling recipe that applies intensive illumination by halogen lamp with power up to 250 W of $n^+/n$ GaAs structure to generate the holes necessary for etching, the resulting electron distribution profile differs from that set during growth for an electron concentration in the $n^+$-layer $>$ 4 $\cdot$ 10$^{18}$ cm$^{-3}$ when using EDTA electrolyte. This difference is due to the appearance and development of etching pits caused by the increase in the degree of defectivity of GaAs layers with increasing concentration of the donor impurity – silicon. To obtain adequate electron distribution profiles in $n^+/n$ GaAs structures it is necessary to limit the illumination up to 25 W.