Ge/Si self-assembled Islands for Photonics Applications

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0958-L03-06

Ge/Si Self-Assembled Islands for Photonics Applications Philippe Boucaud, Moustafa El Kurdi, Xiang Li, Sébastien Sauvage, Xavier Checoury, Sylvain David, Navy Yam, Frédéric Fossard, Daniel Bouchier, and Guy Fishman Institut d'Electronique Fondamentale, CNRS-Univ Paris Sud, Bâtiment 220, Orsay, F-91405, France

ABSTRACT We first present an analysis of the band line-up in the case of SiGe/Si quantum wells and in the case of SiGe/Si self-assembled islands. The conduction and valence band diagrams are obtained from a 30 band k.p Hamiltonian which allows to describe simultaneously conduction and valence band states. The strain field is obtained from a microscopic valence force field theory. The band edge alignment is strongly dependent on the input parameters for this heterosystem. We determine the average valence band offset from photoluminescence measurements of heterostructures grown on relaxed SiGe buffer layers. A type II band line-up is calculated for all Ge compositions in the case of two-dimensional quantum wells and SiGe/Si self-assembled islands. The 30-band formalism allows the determination of the near-infrared interband recombination energy as a function of the self-assembled island structural parameters. We then present recent results obtained by embedding SiGe/Si self-assembled islands in twodimensional photonic crystals. The photoluminescence of GeSi islands acts as an internal probe to characterize the optical properties of silicon-based two-dimensional photonic crystals designed for the near-infrared spectral range. Cavities, defect-free photonic crystals operated at the second Bragg order and two-dimensional photonic crystals fabricated on top of one-dimensional Bragg mirrors (2D + 1D) are described. We show that, in the case of 2D +1D structures, we can control the quality factor of optical modes at the second Bragg order by matching the resonance conditions and controlling the thickness of the layers. Photonic crystals with pure Ge layers are finally described.

INTRODUCTION A growing interest is devoted nowadays to silicon photonics. The development of this field is stimulated by different factors. The microelectronics industry is facing hard challenges to overcome the electrical interconnect bottleneck. Optical interconnects are an alternative possible solution for interchip or intrachip interconnects with specific advantages in terms of bandwidth, heat dissipation and delay. Independently, the huge capacities of the microelectronics industry can lead to the development of novel low cost silicon-based optical components. The prerequisite is the compatibility of the fabrication process with standard CMOS fab environment. The intergration of complex electronic circuitry with photonic circuits is a key advantage for future CMOS-based photonic platforms. 10 Gb/s optical transceivers designed and fabricated in a 0.13 µm CMOS production line have been recently demonstrated.i Many ingredients are behind the recent success of silicon photonics. Silicon is transparent in the near infrared spec