Low-temperature, plasma-free method of sol-gel SiO2 passivation coating film was applied to InGaAsN quantum well microlasers emitting in the 1.2 mu m spectral range. A marked enhancement in their optical performance under optical pumping and current injection was found. For optically pumped microlasers, room-temperature lasing was achieved along with a substantial increase in photoluminescence intensity. In the case of electrically injected microlasers, the threshold current density was significantly reduced from 45.8 kA/cm(2) to 20.1 kA/cm(2). The demonstrated approach offers broad prospects for the development of high-performance InGaAs(N) microlasers for applications in nanophotonics and optoelectronics.