These authors contributed equally to this work.Fully exploiting the silicon photonics platform requires a fundamentally new approach to realize high-performance laser sources that can be integrated directly using wafer-scale fabrication methods. Direct band gap III-V semiconductors allow efficient light generation but the large mismatch in lattice constant, thermal expansion and crystal polarity makes their epitaxial growth directly on silicon extremely complex. Here, using a selective area growth technique in confined regions, we surpass this fundamental limit and demonstrate an optically pumped InP-based distributed feedback (DFB) laser array grown on (001)-Silicon operating at room temperature and suitable for wavelength-division-multiplexing applications. The novel epitaxial technology suppresses threading dislocations and anti-phase boundaries to a less than 20nm thick layer not affecting the device performance. Using an in-plane laser cavity defined by standard top-down lithographic patterning together with a high yield and high uniformity provides scalability and a straightforward path towards cost-effective cointegration with photonic circuits and III-V FINFET logic.The potential of leveraging well-established and high yield manufacturing processes developed initially by the electronics industry has been the main driver fueling the massive research in silicon photonics over 2 the last decade [1][2][3][4][5][6] . From the start of its development though the lack of efficient optical amplifiers and laser sources monolithically integrated with the silicon platform inhibited the widespread adoption in high-volume applications. Solutions relying on flip-chipping prefabricated laser diodes 7,8 or bonding III-V epitaxial material [9][10][11] are now being deployed in commercially available optical interconnects but are less compatible with standard high-volume and low cost manufacturing processes. Approaches focusing on the engineering of group IV materials have achieved optical gain but still require extensive work to reach room temperature lasing at reasonable efficiency [12][13][14] . Therefore, the monolithic integration of direct bandgap III-V semiconductors, well known to be efficient light emitters, with the silicon photonics platform is heavily investigated. However, considerable hurdles need to be overcome. When directly growing III-V semiconductors on silicon substrates, the large lattice mismatch (εInP/Si = 8.06 %), the difference in thermal expansion and the different polarity of the materials result in large densities of crystalline defects including misfit and threading dislocations, twins, stacking faults and anti-phase boundaries, strongly degrading the performance and reducing the lifetime of any device fabricated in the as-grown layers 15 . Several routes to overcome these issues have been proposed. GaP-related materials can be grown on exact (001) silicon substrates with a small lattice mismatch and pulsed laser oscillation around 980 nm up to 120 K 16 has been achieved but shifting the laser...

This study relates to the heteroepitaxy of InP on patterned Si substrates using the defect trapping technique. We carefully investigated the growth mechanism in shallow trench isolation trenches to optimize the nucleation layer. By comparing different recess engineering options: rounded-Ge versus V-grooved, we could show a strong enhancement of the crystalline quality and growth uniformity of the InP semiconductor. The demonstration of III-V heteroepitaxy at scaled dimensions opens the possibility for new applications integrated on Silicon.

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On-chip optical interconnects still miss a high-performance laser monolithically integrated on silicon. Here, we demonstrate a silicon-integrated InP nanolaser that operates at room temperature with a low threshold of 1.69 pJ and a large spontaneous emission factor of 0.04. An epitaxial scheme to grow relatively thick InP nanowires on (001) silicon is developed. The zincblende/wurtzite crystal phase polytypism and the formed type II heterostructures are found to promote lasing over a wide wavelength range.

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