An innovative approach is proposed for epitaxial growth of high Ge content, relaxed Si1−xGex buffer layers on a Si(001) substrate. The advantages of the technique are demonstrated by growing such structures via chemical vapor deposition and their characterization. Relaxed Ge is first grown on the substrate followed by the reverse grading approach to reach a final buffer composition of 0.78. The optimized buffer structure is only 2.8μm thick and demonstrates a low surface threading dislocation density of 4×106cm−2, with a surface roughness of 2.6nm. The buffers demonstrate a relaxation of up to 107%.

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Compressively strained Ge long channel ring-type pMOSFETs with high-κ Si/SiO 2 /HfO 2 /TiN gate stacks are fabricated on Si 0.2 Ge 0.8 virtual substrates. Effective oxide thickness is approximately 1.4 nm with low gate leakage current. A peak hole mobility of 640 cm 2 /V · s and up to a four times enhancement over the Si/SiO 2 universal curve are observed. Parasitic conduction within the Si-cap layers degrades the mobility at large vertical fields, although up to a 2.5 times enhancement over universal remains at a field of 0.9 MV/cm.

We investigate and characterize p-i-n near-infrared photodiodes fabricated in Ge-on-Si by reduced-pressure chemical vapor deposition, a technology compatible with silicon processing. The detectors exhibit remarkably low dark current densities of 1mA/cm(2) at unity reverse bias and high responsivities of 200 mA/W at 1.55 mu m. We evaluated their small-signal resistance, capacitance, and bandwidth as well as eye-diagrams at 2.5 and 10 Gbit/s