We demonstrated the uniformity and stability as well as the high breakdown voltage of 0.1-µm-gate InP HEMTs with a double recess structure. To overcome the drawbacks regarding the uniformity and stability in the double recess structure, an InP passivation layer that functions as an etch-stopper and a surface passivator was successfully applied to the structure. It was confirmed that there was no degradation in the uniformity and stability of device performance for the double recess HEMTs that had the breakdown voltages in the on-state and off-state improved by a factor of 1.6.