Single-mode, highly directional and stable photo- luminescence (PL) emission has been achieved from porous silicon microcavities (PSMs) fabricated by pulsed electro- chemical etching. The full width at half maximum (FWHM) of the narrow PL peak available from a freshly etched PSM is about 9 nm. The emission concentrates in a cone of 10 ◦ around the normal of the sample, with a further reduced FWHM of ∼ 5.6 nm under angle-resolved measurements. Only the resonant peak is present in such angle-resolved PL spectra. No peak broadening is found upon exposure of the freshly prepared PSM to a He−Cd laser beam, and the peak becomes somewhat narrower (∼ 5.4 nm) after the PSM has been stored in an ambient environment for two weeks. At optimized etching parameters, even a 4-nm FWHM is achiev- able for the freshly etched PSM. In addition, scanning elec- tron microscopy (SEM) plane-view images reveal that the single layer porous Si formed by pulsed current etching is more uniform and flatter than that formed by direct current (dc) etching, demonstrated by the well-distributed circular pores with small size in the former in comparison with the ir- regular interlinking pores in the latter. The SEM cross-section images show the existence of oriented Si columns of 10 nm diameter along the etching direction within the active layer, good reproducibility and flat interfaces. It is thus concluded that pulsed current etching is superior to dc etching in ob- taining flat interfaces within the distributed Bragg reflectors because of its minor lateral etching.