Enhanced power performance of enhancement-mode Al/sub 0.5/Ga/sub 0.5/As/In/sub 0.15/Ga/sub 0.85/As pHEMTs using a low-k BCB passivation

Surface passivation technology plays an important role, especially in E-mode pHEMTs applications, and a new passivation technology has been proposed in this study. This novel benzocyclobutene (BCB) passivation layer takes advantage of the low dielectric permittivity (2.7) and a low loss tangent (0.0008). We not only suppress the gate-to-drain leakage current but also improve the device power performance under a high input power swing by using a BCB passivation layer. The passivated 1.0 μm-long gate pHEMTs exhibit a better off-state performance than the unpassivated ones. The maximum output power under a 2.4-GHz operation is 118 mW/mm, with a linear power gain of 11.1 dB and a power-added efficiency is 60%.