ETCH CHARACTERISTICS OF SUCCINIC ACID AMMONIA HYDROGEN-PEROXIDE VERSUS ALUMINUM MOLE FRACTION IN ALGAAS

We have measured the etch rate and selectivity of succinic acid/ammoni a/hydrogen peroxide etchants on AlxGa1-xAs with aluminum mole fraction s of 0.1, 0.2, 0.4, and 0.6. The sensitivity to pH, peroxide concentra tion, and temperature was studied in a regime appropriate for fabricat ing GaAs/AlGaAs optoelectronic devices. The selectivity between Al0.2G a0.8As and Al0.4Ga0.6As increases monotonically over the range of pH s tudied and is greater than 150 at pH 5.3. These results indicate alumi num mole fractions as low as 40% can be used for etch stop layers in G aAs/AlGaAs.