Optical properties of GaP/Si active microdisks containing InGaAs/GaP quantum dots

Taking advantage of low production costs and large integration scale, silicon photonics is a promising way to improve on-chip data routing and reduce electronic consumption. The small lattice mismatch between Si and GaP... [ view full abstract ]

Taking advantage of low production costs and large integration scale, silicon photonics is a promising way to improve on-chip data routing and reduce electronic consumption. The small lattice mismatch between Si and GaP promotes the latter as a good candidate for III-V pseudomorphic integration, but questions remain on the interest of this platform for photonics. In this context, GaP/Si microdisks  constitute a model system to explore the assets of the platform for optics [1].  GaP being an indirect material, nanostructure engineering is required to realize active devices. We presently focus on (In,Ga)As/GaP quantum dots(QDs), which theoretically feature a  cross-over between direct /indirect bandgap emission and type-I/type-II depending on their In content, size and strain field [2], [3]. In this contribution, we investigate optical properties of these QDs by using temperature (Fig. 1) and excitation dependent PL experiments for various growth parameters to probe these electronic states and promote the direct emission. At low temperature, the appearance of a low energy contribution in the emission spectrum is reported. The origins of the PL peaks and their interplay will be discussed in the framework of type-I/type-II and direct/ indirect transitions. Moreover, we demonstrate room temperature photoluminescence of these QDs in a GaP/Si microdisk where the QD layer is located at only 200nm from the III-V/Si interface (Fig. 2) highlighting overall good structural quality of the GaP/Si device.  This research project is supported by the Labex Cominlabs project ANR-10-LABX-07-01 and the OPTOSI ANR project N°12-BS03-002-02.

[1]          P. Guillemé et al., Opt. Express, vol. 24, n^o 13, p. 14608, 2016.

[2]          C. Robert et al., Phys. Rev. B, vol. 94, n^o 7, 2016.

[3]          G. Stracke et al., Appl. Phys. Lett., vol. 104, n^o 12, p. 123107, 2014.

Fig. 1. : Temperature dependent photoluminescence of (In,Ga)As/GaP QDs

Fig. 2. : (left) Scanning electron microscope image of a GaP microdisk on a Si pedestal. (Right) Room temperature photoluminescence of the microdisk