Reliable, efficient electrically pumped silicon-based lasers would enable full integration of photonic and electronic circuits, but have previously only been realized by wafer bonding. Here, we demonstrate the first continuous-wave InAs/GaAs quantum-dot lasers directly grown on silicon substrates with a low threshold current density of 62.5 A/cm 2 , a room-temperature output power exceeding 105 mW, lasing operation up to 120 o C, and over 3,100 hours of continuous-wave operating data collected, giving an extrapolated mean time to failure of over 100,158 hours. The realization of highperformance quantum-dot lasers on silicon is due to the achievement of a low density of threading dislocations on the order of 10 5 cm -2 in the III-V epilayers by combining a nucleation layer and dislocation filter layers with in-situ thermal annealing. These results are a major advance towards silicon-based photonics and photonic-electronic integration, and could provide a route towards reliable and cost-effective monolithic integration of III-V devices on silicon.Increased data throughput between silicon processors in modern information processing demands unprecedented bandwidth and low power consumption beyond the capability of conventional copper interconnects. To meet these requirements, silicon photonics has been under intensive study in recent years 1,2 . Despite rapid progress being made in silicon-based light modulation and detection technology and low-cost silicon optoelectronic integrated devices enabled by the mature CMOS technology 3,4 , an efficient reliable electrically pumped laser on a silicon substrate has remained an unrealized scientific challenge 5 . Group IV semiconductors widely used in integrated circuits, e.g. silicon and germanium, are inefficient light-emitting materials due to their indirect bandgap, introducing a major barrier to the development of silicon photonics. Integration of IIIÐV materials on a silicon platform has been one of the most promising techniques for generating coherent light on silicon. IIIÐV semiconductors with superior optical properties, acting as optical gain media, can be either bonded or epitaxially grown on silicon substrates [6][7][8][9][10][11] , with the latter approach being more attractive for large scale, low-cost, and streamlined fabrication. However, until now, material lattice mismatch and incompatible thermal expansion coefficients between IIIÐV materials and silicon substrates have fundamentally limited the monolithic growth of IIIÐV lasers on silicon substrates by introducing high-density threading dislocations (TDs) 12 .Lasers with active regions formed from III-V quantum dots (QDs), nano-size crystals, can not only offer low threshold current density (J th ) but also reduced temperature sensitivity [13][14][15][16][17] . As shown in Figure 1a, within less than 10 years, the performance of QD lasers has surpassed state-of-the-art quantum-well (QW) lasers developed over the last few decades in terms of J th . QD lasers have now been demonstrated with nearly constan...

We compare InAlAs/GaAs and InGaAs/GaAs strained-layer superlattices (SLSs) as dislocation filter layers for 1.3-μm InAs/GaAs quantum-dot laser structures directly grown on Si substrates. InAlAs/GaAs SLSs are found to be more effective than InGaAs/GaAs SLSs in blocking the propagation of threading dislocations generated at the interface between the GaAs buffer layer and the Si substrate. Room-temperature lasing at ~1.27 μm with a threshold current density of 194 A/cm(2) and output power of ~77 mW has been demonstrated for broad-area lasers grown on Si substrates using InAlAs/GaAs dislocation filter layers.

We report the first room-temperature continuous-wave operation of III-V quantum-dot laser diodes monolithically grown on a Si substrate. Long-wavelength InAs/GaAs quantum-dot structures were fabricated on Ge-on-Si substrates. Room-temperature lasing at a wavelength of 1.28 μm has been achieved with threshold current densities of 163 A/cm(2) and 64.3 A/cm(2) under continuous-wave and pulsed conditions for ridge-waveguide lasers with as cleaved facets, respectively. The value of 64.3 A/cm(2) represents the lowest room-temperature threshold current density for any kind of laser on Si to date.

We report on the first electrically pumped continuous-wave (cw) InAs/GaAs quantum dot (QD) lasers monolithically grown on on-axis Si (001) substrates without any intermediate buffer layers. A 400 nm antiphase boundary (APB) free epitaxial GaAs film with a small root-mean-square (RMS) surface roughness of 0.86 nm was first deposited on a 300 mm standard industry-compatible on-axis Si (001) substrate by metal-organic chemical vapor deposition (MOCVD). The QD laser structure was then grown on this APB-free GaAs/Si (001) virtual substrate by molecular beam epitaxy (MBE). Room-temperature cw lasing at ~1.3 µm has been achieved with a threshold current density of 425 A/cm² and single facet output power of 43 mW. Under pulsed operation, lasing operation up to 102 °C has been realized, with a threshold current density of 250 A/cm² and single facet output power exceeding 130 mW at room temperature.

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III-V semiconductors monolithically grown on Si substrates are expected to be an ideal solution to integrate highly-efficient light-emitting devices on a Si platform. However, the lattice mismatch between III-V and Si generates a high density of threading dislocations at the interface between III-V and Si. Some of these threading dislocations will propagate into the III-V active region and lead to device degradation. By introducing defect filter layers (DFLs), the density of threading dislocations propagating into the III-V layers can be significantly reduced. In this paper, we present an investigation on the development of InGaAs/GaAs strained-layer superlattices as DFLs for 1.3 μm InAs/GaAs quantum-dot lasers monolithically grown on a Si substrate. We compare two broad-area InAs/GaAs quantum-dot lasers with non-optimized and optimized InGaAs/GaAs DFLs. The laser device with optimal DFLs has a lower room-temperature threshold current density of 99 A/cm 2 and higher maximum operation temperature of 88 °C, compared with 174 A/cm 2 and 68 °C for the reference laser.

We present the wafer-scale fabrication of self-catalyzed p-n homojunction 1.7 eV GaAsP core-shell nanowire photocathodes grown on silicon substrates by molecular beam epitaxy with the incorporation of Pt nanoparticles as hydrogen evolution cocatalysts. Under AM 1.5G illumination, the GaAsP nanowire photocathode yielded a photocurrent density of 4.5 mA/cm(2) at 0 V versus a reversible hydrogen electrode and a solar-to-hydrogen conversion efficiency of 0.5%, which are much higher than the values previously reported for wafer-scale III-V nanowire photocathodes. In addition, GaAsP has been found to be more resistant to photocorrosion than InGaP. These results open up a new approach to develop efficient tandem photoelectrochemical devices via fabricating GaAsP nanowires on a silicon platform.

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