Abstract
We have measured the etch rate and selectivity of succinic acid/ammonia/hydrogen peroxide etchants on 
with aluminum mole fractions of 0.1, 0.2, 0.4, and 0.6. The sensitivity to pH, peroxide concentration, and temperature was studied in a regime appropriate for fabricating 
optoelectronic devices. The selectivity between 
and 
increases monotonically over the range of pH studied and is greater than 150 at pH 5.3. These results indicate aluminum mole fractions as low as 40% can be used for etch stop layers in 
.