Enhancing the photoluminescence response of thick Ge-on-Si layers using photonic crystals

Abstract

Abstract More than an order of magnitude enhancement of the room-temperature photoluminescence (PL) signal from rather thick germanium layers grown on Si(001) was obtained through the utilization of 2D photonic crystals (PhCs). A set of PhCs with different periods and filling factors was fabricated and studied using micro-PL spectroscopy. Optical features of the fabricated PhCs were also theoretically modeled using rigorously coupled wave analysis, which allowed us to bring the observed peaks in the PL response into correlation with the different modes of PhC. In particular, we were able to associate the well-resolved peaks in the PL spectra with the optically active modes of the PhCs. The obtained results proved the possibility of using a homogeneously distributed active medium in PhCs without the formation of specially designed cavities in order to redistribute the internal emitted light into the required modes and efficiently extract it in the far field. The relative simplicity and higher tolerance to fabrication imperfections, as well as the large working area of these kinds of PhCs compared to PhCs with microcavities, can be advantageous for creating a PhC-based Si-compatible light source for the telecom band.