Bong-Jin Kuh

Observation of molecular nitrogen in N-doped Ge2Sb2Te5

Ge2Sb2Te5 (GST) film in the crystalline state was nitrogen doped using the reactive sputtering method in order to increase sheet resistance. High-resolution x-ray absorption spectroscopy revealed that molecular nitrogen (N2) existed in the N-doped GST film. This finding implies that both molecular nitrogen and atomic-state nitrogen should be taken into account in understanding the structures of N-doped GST film. The molecular nitrogen is believed to exist at interstitial and vacancy sites, and more likely at grain boundaries.

Si-based optical I/O for optical memory interface

Optical interconnects may provide solutions to the capacity-bandwidth trade-off of recent memory interface systems. For cost-effective optical memory interfaces, Samsung Electronics has been developing silicon photonics platforms on memory-compatible bulk-Si 300-mm wafers. The waveguide of 0.6 dB/mm propagation loss, vertical grating coupler of 2.7 dB coupling loss, modulator of 10 Gbps speed, and Ge/Si photodiode of 12.5 Gbps bandwidth have been achieved on the bulk-Si platform. 2x6.4 Gbps electrical driver circuits have been also fabricated using a CMOS process.