High mobility enhancement mode FET

A method for forming a semiconductor field effect device structure comprising:

• forming a source and a drain region;
• forming a dielectric layer by means of deposition or thermal growth process steps, extending over at least a portion of a channel region comprised between said source and drain regions;
• forming a gate by means of deposition of metal or semiconductor material extending over at least a portion of said dielectric layer;
• wherein said gate is in physical contact with said dielectric layer;
• wherein said gate is at least partially overlapped with at least one of said source and drain regions;
• wherein a semiconductor barrier region is present under said channel region;
• wherein said gate has a work-function substantially equal or greater than the sum of the electron affinity and half energy-gap of said channel region, when said semiconductor field effect device is a n-channel device;
• wherein said gate has a work-function substantially equal or lower than the sum of the electron affinity and half energy-gap of said channel region, when said semiconductor field effect device is a p-channel device, and
• wherein said semiconductor field effect device structure is an enhancement mode field effect device.

A semiconductor field effect device structure comprising:

• a source region and a drain region;
• a channel region between said source and drain regions;
• a semiconductor barrier region under said channel region;
• a dielectric layer extending over at least a portion of said channel region;
• a gate extending over said dielectric layer;
• wherein said gate is in physical contact with said dielectric layer;
• wherein said gate is at least partially overlapped with at least one of said source and drain regions;
• wherein said gate has a work-function substantially equal or greater than the sum of the electron affinity and half energy-gap of said channel region when said semiconductor field effect device is a n-channel device;
• wherein said gate has a work-function substantially equal or lower than the sum of the electron affinity and half energy-gap of said channel region, when said semiconductor field effect device is a p-channel device, and
• wherein said semiconductor field effect device structure is an enhancement mode field effect device.