Single quantum dots are competitive candidates for the realization of highly-pure, highly-indistinguishable, and highly-effcient single-photon sources. To perform quantum information processing using single photons, hundreds of identical single photons are required. Therefore, scalable and integrated single-photon sources are needed. In this project, novel methods for the design and fabrication of scalable nanophotonic devices with integrated quantum emitters have been developed. These devices exhibit outstanding properties as single-photon sources with higher fabrication yield and faster electrical response. Near-ideal single-photon sources in planar nanostructures with small localized electrical gates have been demonstrated. Photonic crystal waveguides have been used to tailor light-matter interaction and achieve near-deterministic operation over a broad wavelength range. An indistinguishability exceeding 97 %, a purity of ¡98 %, and a total effciency of 8.4 % are simultaneously obtained in these devices, thanks to the improved nanofabrication process developed in this work. Several designs of nearunity purity and indistinguishability sources have been realized on-chip. These include special integrated circuits for resonantly exciting the quantum dots via nanophotonic waveguides. Such an excitation scheme enables long-time operation without losing alignment and offers the potential to scale up the number of sources integrated in the same chip. The main figures of merit to assess the quality of single-photon emission and their characterization are discussed. The existing limitations are well understood: for example the purity is mainly limited by the limited suppression of the excitation laser background, while the photon distinguishability is due to the coupling of the quantum dot with its host environment, leading to charge, spin, and phonon noise. In gated devices, the charge noise and spin noise have been significantly suppressed, and only the phonon noise is a fundamental limitation. We experimentally show how indistinguishability changes as a function of temperature in a photonic crystal waveguide and identify various mechanisms involved in the degradation of the emitters’ coherence. At 𝑇 < 10K, the dephasing is induced by the linear phonon coupling, while above 10K, dephasing is dominated by acoustic phonon quadratic coupling enabling virtual transitions in the quantum dot. Optical propagation loss is still the most challenging aspect when considering the total source efficiency. Waveguide loss becomes a serious issue when scaling to multiple sources or larger photonic integrated circuits. In this work, the origin of optical loss in gated nanophotonic waveguides as a function of temperature, wavelength, and external voltage is discussed. We found that the electroabsorption due to the Franz-Keldish effect, is the dominant loss mechanism. A strong surface electric field, induced by Fermi-level pinning, leads to loss over 20 dB/mm at room temperature in un-passivated samples. It is therefore necessary to reduce losses for scaling up further. The thesis reports on the fabrication techniques developed towards building singlephoton sources with state-of-the-art properties. While further scaling in GaAs seems prohibitive due to optical loss, the sources and fabrication methods reported here could be readily used for heterogeneous integration in other material platforms. The results constitute an important step forward in building a fully-scalable photonic integrated platform with applications in quantum computing and simulation.