<p> 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. </p><p> 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&ndash;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. </p><p> 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. </p><p> 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.</p><p>

<p> Nanofabrication through multiphoton absorption has generated considerable interest because of its unique ability to generate 2D and 3D structures in a single laser-direct-write step as well as its ability to generate feature sizes well below the diffraction limited laser spot size. The majority of multiphoton fabrication has been used to create 3D structures of photopolymers which have applications in a wide variety of fields, but require additional post-processing steps to fabricate conductive structures. It has been shown that metal ions can also undergo multiphoton absorption, which reduces the metal ions to stable atoms/nanoparticles which are formed at the laser focal point. When the focus is located at the substrate surface, the reduced metal is deposited on the surface, which allows arbitrary 2D patterning as well as building up 3D structures from this first layer. Samples containing the metal ions can be prepared either in a liquid solution, or in a polymer film. The polymer film approach has the benefit of added support for the 3D metallic structures; however it is difficult to remove the polymer after fabrication to leave a free standing metallic structure. With the ion solution method, free standing metallic structures can be fabricated but need to be able to withstand surface tension forces when the remaining unexposed solution is washed away.</p><p> So far, silver nanowires with resistivity on the order of bulk silver have been fabricated, as well as a few small 3D structures. This research focuses on the surfactant assisted multiphoton reduction of silver ions in a liquid solution. The experimental setup consists of a Coherent Micra 10 Ultrafast laser with 30fs pulse length, 80MHz repetition rate, and a wavelength centered at 800nm. This beam is focused into the sample using a 100x objective with a N.A. of 1.49. Silver structures such as nanowires and grid patterns have been produced with minimum linewidth of 180nm. Silver nanowires with resistivity down to 6x bulk silver have been fabricated. Three-dimensional structures have also been fabricated with up to a 10&micro;m height at a thickness of 500nm. This method can fabricate structures with the possible applications in plasmonic metamaterials, photonic crystals, MEMS/NEMS and micro/nanocircuitry. </p><p>