High-mobility fully depleted thin-film SOS MOSFET's

Transistor characteristics for improved, fully depleted thin-film (100-nm thick) silicon-on-sapphire (SOS) MOSFETs with 25-nm gate oxides were measured for various gate lengths from 15 to 300 K with measurements taken at 10 K intervals. Peak hole mobilities as high as 250 cm/sup 2//V-s at 300 K and 1700 cm/sup 2//V-s at 77 K were measured in p-channel MOSFETs. Measurements of corresponding n-channel devices of the same dimensions have revealed electron mobilities of 360 cm/sup 2//V-s at 300 K and 590 cm/sup 2//V-s at 77 K. The high hole mobility behavior unique to SOS may be attributed to stress in the thin silicon film due to the sapphire interface.