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 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 and operation up to 120 °C. Over 3,100 h of continuous-wave operating data have been collected, giving an extrapolated mean time to failure of over 100,158 h. The realization of high-performance quantum dot lasers on silicon is due to the achievement of a low density of threading dislocations on the order of 105 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 reliable and cost-effective silicon-based photonic–electronic integration.

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Electrically pumped continuous-wave III–V quantum dot lasers on silicon

The physics of the growth mechanisms, characterization of epitaxial structures and device properties of GaAs and other compound semiconductors on Si are reviewed in this paper. The nontrivial problems associated with the heteroepitaxial growth schemes and methods that are generally applied in the growth of lattice mismatched and polar on nonpolar material systems are described in detail. The properties of devices fabricated in GaAs and other compound semiconductors grown on Si substrates are discussed in comparison with those grown on GaAs substrates. The advantages of GaAs and other compound semiconductors on Si, namely, the low cost, superior mechanical strength, and thermal conductivity, increased wafer area, and the possibility of monolithic integration of electronic and optical devices are also discussed.

Gallium arsenide and other compound semiconductors on silicon

Growing a group III–V quantum dot laser directly on a group IV substrate could provide silicon photonics with a convenient new form of laser source for use in optoelectronic circuitry.

Long-wavelength InAs/GaAs quantum-dot laser diode monolithically grown on Ge substrate

We report an investigation of the materials properties of GaAs on Si epitaxial layers. By using properly oriented substrates, we have found that a substantial reduction in the density of threading dislocations can be achieved. In the presence of steps, dislocations with their Burgers vectors in the (100) substrate plane are preferentially generated, which are more effective in accommodating lattice mismatch and do not thread into the epitaxial layer. We have also found that the density of threading dislocations can be reduced significantly by the use of GaAs/InGaAs pseudomorphic superlattices. Using these techniques, dislocation densities of as low as 103–104 cm−2 have been achieved in 2‐μm‐thick GaAs on Si epitaxial layers. In growth on nominal (100) orientations, where it is known that single atomic steps dominate, we have found no evidence of antiphase domains by transmission electron microscopy or chemical etching. This result suggests that it may not be energetically favorable for antiphase domains t...

Material properties of high‐quality GaAs epitaxial layers grown on Si substrates

We report the first operation of an electrically pumped 1.3-μm InAs/GaAs quantum-dot laser epitaxially grown on a Si (100) substrate. The laser structure was grown directly on the Si substrate by molecular beam epitaxy. Lasing at 1.302 μm has been demonstrated with threshold current density of 725 A/cm2 and output power of ~26 mW for broad-area lasers with as-cleaved facets at room temperature. These results are directly attributable to the optimized growth temperature of the initial GaAs nucleation layer.

1.3-μm InAs/GaAs quantum-dot lasers monolithically grown on Si substrates.

Using molecular beam epitaxy, we have successfully grown device quality GaAs/AlGaAs on (100)‐oriented Ge and Si substrates. Modulation doped field effect transistors have been fabricated from these layers which exhibit room‐temperature transconductances as high as 160 and 170 mS/mm for layers on Ge and Si, respectively, and showed no looping in either case. At 77 K, these values rose to 345 and 275 mS/mm for Ge and Si, respectively. Analysis by transmission electron microscopy of layers grown on Ge showed that the antiphase disorder was contained within the 250‐A‐thick initial layer which was grown at a 0.1‐μ/h growth rate at a substrate temperature of 500 °C. For both the layers grown on Si and Ge specular surface morphologies were obtained. The photoluminescence of GaAs/AlGaAs quantum wells grown on Si and Ge was similar in intensity to the same quantum well structures grown on GaAs. In quantum wells grown on Ge, the luminescence was dominated by a donor‐acceptor recombination at 1.479 eV, which appears to be Ge0Ga ‐Ge0As. These results show that high‐quality GaAs/AlGaAs is obtainable on nonpolar substrates, which has important implications for the monolithic integration of III‐V’s with Si.

Growth and properties of GaAs/AlGaAs on nonpolar substrates using molecular beam epitaxy

The optical properties of ${\mathrm{GaAs}}_{\mathrm{x}}$${\mathrm{Sb}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$ alloys grown across the entire concentration range by multitarget sputter deposition are reported. X-ray diffraction, optical absorption, and Raman spectra show the samples to be single-crystal, single-phase alloys for all x, including those in the miscibility gap. Alloy lattice constants are found to vary linearly with concentration. The direct \ensuremath{\Gamma}-point energy gaps, determined from optical-absorption measurements, show significant negative bowing. Contrary to previous reports, the Raman spectra exhibit two-mode behavior throughout, including a local mode of As in GaSb and a resonant mode of Sb in GaAs. An analysis of peak frequencies and line shapes versus concentration is given in the context of disorder effects. We observe broadenings much less severe and asymmetric than those seen in similar systems and usually interpreted in terms of k\ensuremath{\ne}0 density-of-states activation. The observed adherence to zone-center selection rules for all x, suggests a more accurate interpretation to be one involving the k\ensuremath{\approxeq}0 spectral projection of the density of states.

Raman scattering and optical-absorption studies of the metastable alloy system GaAs x Sb 1 − x

We present Raman-scattering and electron-diffraction results in a study of the structural ordering of single-crystal metastable (${\mathit{A}}^{\mathrm{III}}$${\mathrm{B}}^{\mathrm{V}}$${)}_{1\mathrm{\ensuremath{-}}\mathit{x}}$(${\mathrm{C}}_{2}^{\mathrm{IV}}$${)}_{\mathit{x}}$ alloys. Amorphous-like Raman linewidths are observed, indicative of the severe substitutional disorder in these alloys. Increased violation of the normal zinc-blende-polarization selection rules, relative to that observed in III-V ternary alloys, is attributed to the enhanced electronic disorder in the III-IV-V system. Anomalies in the composition dependence of the Raman line shapes at x\ensuremath{\approxeq}0.30 and x\ensuremath{\approxeq}0.70 imply qualitative changes in the ordering at these compositions. Transmission electron microscopy results are presented which give insight into the nature of these changes. Our results are discussed in the context of competing theoretical models proposed for this system.

Raman-scattering and electron-microscopy study of composition-dependent ordering in metastable (AIIIBV)1-x(CIII2)x alloys.

In an extension of earlier work (1) we have used Raman Scattering to reveal structural information in mixed, metastable, crystalline [GaSb]1-xGe2x=[Ga1-xGex] [Sb1-xGex]. These alloys were deposited on GaAs substrates using a multitarget r.f. sputtering system (2).

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T. C. McGlinn

Papers

Growth and properties of GaAs/AlGaAs on nonpolar substrates using molecular beam epitaxy

Raman scattering and optical-absorption studies of the metastable alloy system GaAs x Sb 1 − x

Raman-scattering and electron-microscopy study of composition-dependent ordering in metastable (AIIIBV)1-x(CIII2)x alloys.

Raman Scattering from Metastable (Gasb)1-xGe2x Alloys

Resonant-Raman-scattering study of disorder effects in AlxGa1-xAs alloys.