The damage induced by the passivation process has been evaluated and compared by admittance and deep level transient spectroscopies in GaInAs planar photodiodes passivated by a silicon nitride film. The comparison is based on three deposition techniques: the chemical vapor deposition (CVD), the plasma‐enhanced CVD (PECVD), and the ultraviolet activated CVD (UVCVD). Two deep levels, with properties and concentration which are found to be strongly dependent on the passivation techniques, are observed: The first, located atEc−0.35 eV is detected in PECVD and UVCVD passivated diodes and attributed to the GaInAs surface degradation resulting from the deposition process. The second, located atEc−0.19 eV appears only on CVD diodes and could be related to the high‐temperature treatment specific to this technique.