ALXGA1-XAS GAAS HETEROSTRUCTURE CHARACTERIZATION BY WET CHEMICAL ETCHING

Selective wet chemical etching of the AlxGa1-xAs/GaAs system has been applied to heterostructure characterization. Samples of LPE grown AlGa As/GaAs laser double-heterostructures and separate confinement heteros tructures as well as antiresonant reflecting optical waveguides hetero structures were treated with ''I2 solution'' (I2:KI:H2O) and hydrochlo ric acid. These compounds selectively etch the ternary AlxGa1-xAs laye rs, but with different'' threshold composition'' x(th) values (the x v alue is that above which the etching rate of a given compound increase s sharply). Selectively etched samples have been examined by SEM. The experimental dependence of etching rate on the x value for I2 solution has been derived. From this dependence, the x composition of any tern ary layer can be estimated simply. Observations were made of the ''mic roscopic'' properties of the heterostructure, such as the smoothness o f the interfaces and the uniformity of layers. All imperfections resul ting from the growth process, such as interface perturbations or compo sitional nonuniformity of layers, are clearly seen. An additional adva ntage of this etching technique is its simplicity. It allows quick exa mination of grown heterostructure for the selection of wafers for furt her processing.