We examined the effect of SiO₂ passivation on the parameters of mesa heterostructure InAs/InAsSbP photodiodes with a spectral responsivity 50% cut off at 3.5 µm at 295 K, specific to the InAs absorber layer. The R₀A product was found to increase by 30% after passivation of the devices of 113 µm in diameter, up to 0.9 Ωcm², while for those with a diameter of 1.13 mm, R₀A of 2.2 Ωcm² was achieved, with a value of D* > 3×10⁹ cmHz^1/2/W at the peak of the spectrum, 1 kHz, 0 V bias, 295 K. To the best of our knowledge, this is the highest R₀A value at room temperature reported to date for a photodiode with an InAs absorber.