title: Wurtzite-Phased InP Micropillars Grown on Silicon with Low Surface Recombination Velocity.
abstract: The direct growth of III-V nanostructures on silicon has shown great promise in the integration of optoelectronics with silicon-based technologies. Our previous work showed that scaling up nanostructures to microsize while maintaining high quality heterogeneous integration opens a pathway toward a complete photonic integrated circuit and high-efficiency cost-effective solar cells. In this paper, we present a thorough material study of novel metastable InP micropillars monolithically grown on silicon, focusing on two enabling aspects of this technology-the stress relaxation mechanism at the heterogeneous interface and the microstructure surface quality. Aberration-corrected transmission electron microscopy studies show that InP grows directly on silicon without any amorphous layer in between. A set of periodic dislocations was found at the heterointerface, relaxing the 8% lattice mismatch between InP and Si. Single crystalline InP therefore can grow on top of the fully relaxed template, yielding high-quality micropillars with diameters expanding beyond 1 μm. An interesting power-dependence trend of carrier recombination lifetimes was captured for these InP micropillars at room temperature, for the first time for micro/nanostructures. By simply combining internal quantum efficiency with carrier lifetime, we revealed the recombination dynamics of nonradiative and radiative portions separately. A very low surface recombination velocity of 1.1 × 10(3) cm/sec was obtained. In addition, we experimentally estimated the radiative recombination B coefficient of 2.0 × 10(-10) cm(3)/sec for pure wurtzite-phased InP. These values are comparable with those obtained from InP bulk. Exceeding the limits of conventional nanowires, our InP micropillars combine the strengths of both nanostructures and bulk materials and will provide an avenue in heterogeneous integration of III-V semiconductor materials onto silicon platforms.
authors.affiliation: Department of Electrical Engineering and Computer Sciences, University of California at Berkeley , Berkeley, California 94720, United States.
authors.forename: Kun
authors.initials: K
authors.lastname: Li
authors.affiliation: Department of Electrical Engineering and Computer Sciences, University of California at Berkeley , Berkeley, California 94720, United States.
authors.forename: Kar Wei
authors.initials: KW
authors.lastname: Ng
authors.affiliation: Department of Electrical Engineering and Computer Sciences, University of California at Berkeley , Berkeley, California 94720, United States.
authors.forename: Thai-Truong D
authors.initials: TT
authors.lastname: Tran
authors.affiliation: Department of Electrical Engineering and Computer Sciences, University of California at Berkeley , Berkeley, California 94720, United States.|Department of Electronic Engineering, Tsinghua University , Beijing 100084, P. R. China.
authors.forename: Hao
authors.initials: H
authors.lastname: Sun
authors.affiliation: Department of Electrical Engineering and Computer Sciences, University of California at Berkeley , Berkeley, California 94720, United States.
authors.forename: Fanglu
authors.initials: F
authors.lastname: Lu
authors.affiliation: Department of Electrical Engineering and Computer Sciences, University of California at Berkeley , Berkeley, California 94720, United States.
authors.forename: Connie J
authors.initials: CJ
authors.lastname: Chang-Hasnain
mesh_terms: D046529:Microscopy, Electron, Transmission; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology; D053770:Nanowires / Q000737:chemistry* / Q000648:ultrastructure; D012666:Semiconductors; D012825:Silicon / Q000737:chemistry*
chemical_list: D012825:Silicon
keywords: InP nanowire/nanoneedle/nanopillar; interface; silicon; surface recombination velocity; wurtzite