Ge-on-Si optoelectronics

• Published in: Thin solid films Vol. 520; no. 8; pp. 3354 - 3360
• Main Authors: Liu, Jifeng, Camacho-Aguilera, Rodolfo, Bessette, Jonathan T., Sun, Xiaochen, Wang, Xiaoxin, Cai, Yan, Kimerling, Lionel C., Michel, Jurgen
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01.02.2012; Elsevier
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Defects and impurities: doping, implantation, distribution, concentration, etc; Electroluminescence; Electronics; Exact sciences and technology; Germanium; Laser; Modulator; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optoelectronic devices; Optoelectronics; Other luminescence and radiative recombination; Photodetector; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Strain; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Germanium; Optoelectronics; Modulator; Photodetector; Laser; Strain; Epitaxy; Electroluminescence; Nitrogen addition; Review; Electroabsorption; Selective growth; Energetic efficiency; Bandwidth; Avalanche photodiodes; Optoelectronic device; Silicon; Defect density; Optoelectronic properties; Epitaxial film; Gallium phosphide; Growth defect; Waveguide; Franz Keldysh effect; Tensile stress; p i n photodiodes
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2011.10.121

Electronic–photonic synergy has become an increasingly clear solution to enhance the bandwidth and improve the energy efficiency of information systems. Monolithic integration of optoelectronic devices is the ideal solution for large-scale electronic–photonic synergy. Due to its pseudo-direct gap behavior in optoelectronic properties and compatibility with Si electronics, epitaxial Ge-on-Si has become an attractive solution for monolithic optoelectronics. In this paper we will review recent progress in Ge-on-Si optoelectronics, including photodetectors, electroabsorption modulators, and lasers. The performance of these devices has been enhanced by band-engineering such as tensile strain and n-type doping, which transforms Ge towards a direct gap material. Selective growth reduces defect density and facilitates monolithic integration at the same time. Ge-on-Si photodetectors have approached or exceeded the performance of their III–V counterparts, with bandwidth-efficiency product >30GHz for p-i-n photodiodes and bandwidth-gain product >340GHz for avalanche photodiodes. Enhanced Franz–Keldysh effect in tensile-strained Ge offers ultralow energy photonic modulation with <30fJ/bit energy consumption and >100GHz intrinsic bandwidth. Room temperature optically-pumped lasing as well as electroluminescence has also been achieved from the direct gap transition of band-engineered Ge-on-Si waveguides. These results indicate that band-engineered Ge-on-Si is promising to achieve monolithic active optoelectronic devices on a Si platform.