Large data centers interconnect bottlenecks are dominated by the switch I/O BW and the front panel BW as a result of pluggable modules. To overcome the front panel BW and the switch ASIC BW limitation one approach is to either move the optics onto the mid-plan or integrate the optics into the switch ASIC. Over the last 4 years, VCSEL based optical engines have been integrated into the packages of large-scale HPC routers, moderate size Ethernet switches, and even FPGA's. Competing solutions based on Silicon Photonics (SiP) have also been proposed for integration into HPC and Ethernet switch packages but with better integration path through the use of TSV (Through Silicon Via) stack dies. Integrating either VCSEL or SiP based optical engines into complex ASIC package that operates at high temperatures, where the required reliability is not trivial, one should ask what is the technical or the economic advantage before embarking on such a complex integration. High density Ethernet switches addressing data centers currently in development are based on 25G NRZ signaling and QSFP28 optical module that can support up to 3.6 Tb of front panel bandwidth.

No abstract

No abstract

No abstract

AlGaAs/GaAs heterojunction bipolar transistors with different base doping concentrations grown by gas source molecular beam epitaxy were fabricated and characterized at dc and high frequency. Three different base doping concentrations; 5×1018, 1×1019, and 5×1019 cm−3 doped with Be were used for the characterization with the same structural and process parameters, including 0.2 μm base width. Minority electron mobilities in heavily doped p type were measured as 1.1×103, 1.3×103, and 3×103 cm2 V/s for 5×1018, 1×1019, and 5×1019 cm−3, respectively, by using the current gain cutoff frequency (fT) which agrees well with theoretical predictions in heavily doped p-type GaAs. Combining dc and high frequency measurements, electron lifetimes of 1.2×10−9, 5.5×10−10, and 2×10−11 s have been obtained for these three dopings, respectively.