A surface-illuminated photoconductive detector based on Ge 0.9 Sn 0.1 quantum wells with Ge barriers grown on a silicon substrate is demonstrated. Photodetection up to 2.2µm is achieved with a responsivity of 0.1 A/W for 5V bias. The spectral absorption characteristics are analyzed as a function of the GeSn/Ge heterostructure parameters. This work demonstrates that GeSn/Ge heterostructures can be used to developed SOI waveguide integrated photodetectors for short-wave infrared applications. 2012 Optical Society of America References and links1. J. Menendez and J. Kouvetakis "Type-I Ge/Ge1−x−ySixSny strained-layer hetero-structures with a direct Ge Bandgap", Applied Physics Letters, 85(7), 1175-1177 (2004). 2. G. Sun, R. A. Soref, H. H. Cheng, "Design of a Si-based lattice-matched room temperature GeSn/GeSiSn multiquantum-well mid-infrared laser diode", Optics Express 18(19), 19957-19965 (2010). 39(3), 1871-1883, (1989). 14. M. Krijn, "Heterojunction band offsets and effective masses in III-V quaternary alloys" Semiconductor Science and Technology, 6(1), 27-31 (1991

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We have investigated Sn precipitation and strain relaxation behaviors in the growth of Ge1−xSnx layers on virtual Ge substrates (v-Ge) for strain engineering of Ge. By varying misfit strain at Ge1−xSnx∕v-Ge and Ge1−ySny∕Ge1−xSnx interfaces, we found that a critical misfit strain controls the onset of Sn precipitation at a given thickness of the Ge1−xSnx layer. A compositionally step-graded method, in which the critical misfit strain is taken into account, was applied to the growth of strain-relaxed Ge1−xSnx layers on v-Ge. Postdeposition annealing at each growth step led to lateral propagation of threading dislocations preexisting in the layer and originating from v-Ge, which resulted in high degree of strain relaxation. An epitaxial Ge layer was grown on the strain-relaxed Ge1−xSnx layer and an in-plane tensile strain of 0.68% was achieved.

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Abstract-In this letter, we describe the use of a germaniumon-silicon waveguide platform to realize an arrayed waveguide grating (AWG) operating in the 5 µm wavelength range, which can be used as a wavelength multiplexer for mid-infrared (midIR) light engines or as the core element of a midIR spectrometer. Ge-on-Si waveguide losses in the range 2.5-3.5 dB/cm for TE polarized light and 3-4 dB/cm for TM polarized light in the 5.15-5.4 µm wavelength range are reported. A 200 GHz channel spacing 5-channel AWG with an insertion loss/crosstalk of 2.5/3.1 dB and 20/16 dB for TE and TM polarization, respectively, is demonstrated.

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Abstract-In this paper we discuss silicon-based photonic integrated circuit technology for applications beyond the telecommunication wavelength range. Silicon-on-insulator and germaniumon-silicon passive waveguide circuits are described, as well as the integration of III-V semiconductors, IV-VI colloidal nanoparticles and GeSn alloys on these circuits for increasing the functionality. The strong nonlinearity of silicon combined with the low nonlinear absorption in the mid-infrared is exploited to generate picosecond pulse based supercontinuum sources, optical parametric oscillators and wavelength translators connecting the telecommunication wavelength range and the mid-infrared.

Organic electroluminescence (EL) devices were fabricated using a bis(2-methyl-8-quinolinato) aluminum hydroxide complex [Al(Mq) 2 OH] as the light-emitting material. The device exhibits bright blue EL at a peak wavelength of 485 nm. A maximum luminance of about 14,000 cd/m 2 can be achieved at a driving current density of 480 mA/cm 2 . The efficiency of the device is about 4.6 cd/A. Possible mechanisms of EL blue shift of Al(Mq) 2 OH with respect to Alq 3 are discussed.