Abstract
Several wet etching solutions for AlGaP of different compositions have been studied. 
is found to etch in HF, 
, hyphosphorous acid 
, HCl, KOH, and 1% 
(MeOH). Etching of 
in HCl is reaction limited with an activation energy of ∼54.4 kJ/mol. At fixed conditions, the etch rates of 
vary exponentially with x in HF and HCl, while in 1% 
and mixtures of HCl and 
the etch rates follow a linear dependence on AlP mole fraction. HF has been found to be a good etchant for AlGaP over InGaP or AlInP with high selectivity, while HCl is useful for the reverse case. The use of 1% 
or the mixtures of HCl and 
provides little selectivity between AlGaP, InGaP, AlInP, and GaAs.