High-energy resolution x-ray photoelectron spectroscopy and photoluminescence have been used to investigate the properties of InGaAs (100) after different surface treatments using hydrofluoric acid (HF) and ultraviolet (UV)-ozone. The efficiency of these treatments was then evaluated using the leakage currents and the current gain of InGaAs/InP heterojunction bipolar transistors (HBTs). Although the effects on InGaAs material properties differ, they both improved the current gain of large area HBTs, Subsequent dielectric depositions induced a drastic degradation of the device characteristics, demonstrating the noncompatibility of these treatments with plasma-enhanced chemical vapor deposition (PECVD) processes. By appropriately combining the W-ozone and HF treatments, a successful passivation can be achieved even under PECVD deposition.