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III-V optoelectronic device integration in a CMOS post-process compatible manner is important for the intimate integration of silicon-based electronic and photonic integrated circuits. The low temperature, self-catalyzed growth of high crystalline quality Wurtzite-phase InP nanopillars directly on silicon presents a viable approach to integrate high performance nano-optoelectronic devices.For the optical transmitter side of the photonic link, InGaAs quantum wells have been grown in a core-shell manner within InP nanopillars. Position-controlled growth with varying pitch is used to systematically control emission wavelength across the same growth substrate. These nanopillars have been fabricated into electrically-injected quantum well in nanopillar LEDs operating within the silicon transparent 1400-1550 nm spectral window and efficiently emitting micro-watts of power. A high quality factor (Q ~ 1000) undercut cavity quantum well nanolaser is demonstrated, operating in the silicon-transparent wavelength range up to room temperature under optical excitation.We also demonstrate an InP nanopillar phototransistor as a sensitive, low-capacitance photoreceiver for the energy-efficient operation of a complete optical link. Efficient absorption in a compact single nanopillar InP photo-BJT leads to a simultaneously high responsivity of 9.5 A/W and high 3dB-bandwidth of 7 GHz.For photovoltaic energy harvesting, a sparsely packed InP nanopillar array can absorb ~90% of the incident light because of the large absorption cross section of these near-wavelength nanopillars. Experimental data based on wavelength and angle resolved integrating sphere measurements will be presented to discuss the nearly omnidirectional absorption properties of these nanopillar arrays.

The heterogeneous integration of optoelectronic and electronic circuits is poised to transform personal electronics because it will not only enable a vast range of otherwise unattainable capabilities, but will also reduce power consumption, weight and size. Monolithic integrations of high-quality III-V materials with single and poly-crystalline silicon are therefore highly desirable. Direct growth of III-V on silicon substrates has been very challenging because of high epitaxy temperatures that are incompatible with CMOS circuits. Moreover, the large mismatches of lattice constants and thermal expansion coefficients between III-V compounds and silicon cause compromises in reliability and performance. As for poly-silicon, the lack of long-range crystalline coherency in the substrate makes high-quality III-V epitaxial deposition impossible. As such, there has been a focus on growing three-dimensional nanostructures, which show great promise to overcome these difficulties.In this dissertation, a novel growth mechanism that yields catalyst-free, self-assembled, single-crystalline nanoneedles and nanopillars on dissimilar substrates will be presented. At CMOS-compatible growth temperatures (400 ~ 455 oC), single-crystalline InGaAs and InP nanostructures are grown on silicon and poly-silicon substrates via metalorganic chemical vapor deposition. Unlike nanowires synthesized with vapor-liquid-solid or selective area growth, the nanostructures expand in both axial and radial directions simultaneously. On top of silicon, these core-shell nanostructures can scale beyond a micron in diameter while maintaining pure wurtzite crystal phase. This high-quality growth is very unusual considering over 6% lattice mismatch between III-V and silicon. More surprisingly, single crystalline InGaAs nanopillars with base diameter far exceeding the substrate crystal grain size can be grown directly on poly-silicon. We study these seemingly impossible heterogeneous growths extensively by examining the crystal lattice at the hetero-interfaces via high-resolution transmission electron microscopy. Discussions on stress-relaxing mechanism, nanostructure nucleation schemes as well as alloy composition uniformity will be presented.With the excellent crystalline quality, InGaAs and InP nanostructures exhibit extraordinary optical properties. Lasing is achieved, for the first time, in as-grown InGaAs and InP nanopillars monolithically synthesized on silicon and poly-silicon. Nanopillar-based devices with respectable diode ideality factor and extremely low dark currents are developed directly on top of silicon. Demonstrations of optoelectronic functionalities including light emission, detection and photovoltaics will be presented. The findings in this work open up a new chapter in the heterogeneous integration of lattice-mismatched materials and their device structure design.

Over the past few decades, semiconductor lasers have relentlessly followed the path towards miniaturization. Smaller lasers are more energy efficient, are cheaper to make, and open up new applications in sensing and displays, among many other things. Yet, up until recently, there was a fundamental problem with making lasers smaller: purely semiconductor lasers couldn't be made smaller than the diffraction limit of light. In recent years, however, metal-based lasers have been demonstrated in the nanoscale that have shattered the diffraction limit. As optical materials, metals can be used to either reflect light (metal-optics) or convert light to electrical currents (plasmonics). In both cases, metals have provided ways to squeeze light beyond the diffraction limit. In this dissertation, I experimentally demonstrated one nanolaser based on plasmonic transduction and another laser based on metal-optic reflection.To create coherent plasmons, I designed a nanolaser based on a plasmonic bandgap defect state inside a surface plasmonic crystal. In a one-dimensional periodic semiconductor beam, I was able to confine surface plasmons by interrupting the periodicity of the crystal. These confined surface plasmons then underwent laser oscillations in effective mode volumes as small as 0.007 cubic wavelengths. At this electromagnetic volume, energy was squeezed 10 times smaller than those possible in similar photonic crystals that do not utilize metal. This demonstration should pave the way for achieving engineered nanolasers with deep-subwavelength mode volumes and enable plasmonic crystals to become attractive platforms for designing plasmons.After achieving large reductions in electromagnetic mode volumes, I switched to a metal-optics-based nanolaser design to further reduce the physical volumes of small light sources. The semiconductor nanopatch laser achieved laser oscillations with subwavelength-scale physical dimensions (0.019 cubic wavelengths) and effective mode volumes (0.0017 cubic wavelengths). The ultra-small laser volume is achieved with the presence of nanoscale metal patches which suppress electromagnetic radiation into free-space and convert a leaky cavity into a highly-confined subwavelength optical resonator. The nanopatch laser, with its world-record-breaking small physical volume, has exciting implications for data storage, biological sensing, on-chip optical communication, and beyond.