M-S. Rouifed

10-Gb/s Ge/SiGe Multiple Quantum-Well Waveguide Photodetector

The authors report on high speed operation of a Ge/SiGe multiple quantum-well waveguide photodetector. At -3 V, 10 Gb/s operation is demonstrated at wavelengths of 1405 and 1420 nm with a responsivity as high as 0.8 A/W. The device, 3 μm wide and 80 μm long, exhibits a dark current of 474 nA at a reverse bias of -1 V. These results pave the way for the use of Ge/SiGe multiple quantum-well structures as efficient active waveguide devices in silicon compatible integrated circuits.

Strong quantum-confined Stark effect from light hole related direct-gap transitions in Ge quantum wells

A strong quantum-confined Stark effect (QCSE) from light hole related transitions at the Γ point (LH1-cΓ1) in Ge/Si0.15 Ge 0.85 multiple quantum wells is demonstrated from both photocurrent and optical transmission measurements. Our experimental results show a large and sharp optical absorption peak due to LH1-cΓ1 transitions, and its associated strong absorption change based on the QCSE. By exploiting LH1-cΓ1 transitions, optical modulators with improved compactness and competitive extinction ratio and optical loss can be envisioned for low energy chip-scale optical interconnect applications.

Low energy consumption and high speed germanium-based optoelectronic devices

Summary form only given. Silicon photonics has generated a strong interest in recent years, mainly for optical telecommunications and optical interconnects in microelectronic circuits. The main rationales of silicon photonics are the reduction of photonic system costs and the increase of the number of functionalities on the same integrated chip by combining photonics and electronics. In the group IV materials, germanium (Ge) has been identified as a promising material to cost-effectively enhance the performance of Si electronic and photonic integrated circuits (IC) [1,2]. In optics, despite being an indirect-gap semiconductor, Ge may play a key role enabling future chip scale optical interconnects to meet aggressive requirements in terms of power consumption, data density, speed, reliability and monolithic integration with silicon [2]. Strong light detection [3], modulation [4], and emission [5] capabilities around C and L telecommunication wavelength bands were shown using Ge direct-gap transitions of bulk Ge on Si. A new promising approach is to employ Ge/SiGe quantum wells (QWs). Indeed, such heterostructures were shown to further enhance light modulation based on quantum confined Stark effect (QCSE) using the direct-gap transition of Ge multiple quantum wells (MQW) embedded in a vertical p-i-n diode [6,7]. Light modulation, detection, and emission can be obtained with both Ge platforms.In this paper, we focus on the modulation performances and DC and high speed modulation performances of the Ge/SiGe MQW waveguide were investigated (figure 1a and 1b). The epitaxial growth of such Ge/SiGe stack was performed using LEPECVD. The Ge/SiGe MQW modulator exhibit a wide spectral range with an ER greater than 10 dB with only 12% overlap factor between the optical mode and the MQW. High speed modulation performance from Ge/SiGe MQWs was demonstrated up to 23 GHz in waveguide configuration at wavelengths around 1.4 μm. The working wavelength can be tuned according to the QW configuration and modulation has been also demonstrated at 1.3μm. Recent results on waveguide integration will be presented and good performance of optical link will be reported.

Measurement of room temperature electroluminescence from Ge quantum well waveguides

Room temperature direct gap electroluminescence (EL) from Ge quantum well waveguides is reported. The excitonic transition and dependence of EL on injection currents and temperature are observed. EL is shown to have a TE polarization.

Ge quantum well electro-absorption modulator with 23 GHz bandwidth

A 23 GHz Ge/SiGe multiple quantum well electro-absorption waveguide modulator is demonstrated with 10 dB extinction ratio (ER). 9 dB ER is achieved with 1V swing with energy consumption limited to 108 fJ per bit.

High speed electro-absorption modulator based on quantum-confined stark effect from Ge/SiGe multiple quantum wells

A 90 μm long 23 GHz Ge/SiGe modulator using the QCSE in waveguide configuration was demonstrated with an ER higher than 10 dB for a wide spectral range. Energy consumption was only 108 fJ/bit.