Etching investigations into the natural cleaved faces of (Ga, Al) As/Ga As heterostructures

The etching of /110/ cleaved faces of (Ga, Al) As/GaAs heterostructures with and without an additional pn-junction. The etching agents are dilute NHO3 and mixtures of NH3 and H2O2. The lines appearing in the etch patterns are attributed to the related steep changes in the physicochemical features of the crystals. The etch patterns can be correlated with the aluminum concentration profiles throughout the epitaxial layers as obtained by electron microprobe analysis. The optimum temperatures, times and compositions of the etch solutions are given. Preferential etching of GaAs by NH3/H2O2 mixtures is discussed.