Self-aligned germanium MOSFETs using a nitrided native oxide gate insulator

The fabrication and performance of dummy-gate self-aligned germanium MOSFETs utilizing a native germanium oxynitride gate insulator is reported. Based on device characteristics, channel mobility at 300 K is estimated as 940 cm/sup 2//Vs. Common-source characteristics show good saturation and turn-off, and do not exhibit looping or other anomalies. It is felt these results suggest that integration of germanium MOSFETs with photodiodes for monolithic optical-fiber receivers operating at 1.3- mu m wavelength should be possible. The results also indicate that the bulk mobility advantage which germanium exhibits relative to silicon carries over in some measure to FET channel mobility. >