Transistors having buried N-type and P-type regions beneath the source region and methods of fabricating the same

A unit cell of a metal-semiconductor field-effect transistor (MESFET), comprising:

• a silicon carbide (SiC) MESFET having a source region, a drain region and a gate contact, the gate contact being between the source region and the drain region and on a channel layer of n-type conductivity SiC;
• a p-type conductivity SiC region beneath the source region and having an end that extends towards the drain region, the p-type conductivity SiC region being spaced apart from the n-type conductivity SiC channel layer and being electrically coupled to the source region;
• and
• an n-type conductivity SiC region on the p-type conductivity SiC region beneath the source region and extending toward the drain region without extending beyond the end of the p-type conductivity SiC region.

A method of forming a metal-semiconductor field-effect transistor (MESFET), comprising:

• forming a MESFET having a source region, a drain region and a gate contact, the gate contact being between the source region and the drain region and on an n-type conductivity channel layer;
• forming a p-type conductivity region beneath the source region and having an end that extends towards the drain region, the p-type conductivity region being spaced apart from the n-type conductivity channel layer and being electrically coupled to the source region;
• and
• forming an n-type conductivity region on the p-type conductivity region beneath the source region and extending toward the drain region without extending beyond the end of the p-type conductivity region.

A unit cell of a transistor, comprising:

• a transistor having a source region, a drain region and a gate contact, the gate contact being between the source region and the drain region and on an n-type conductivity channel layer;
• a p-type conductivity region beneath the source region and having an end that extends towards the drain region, the p-type conductivity region being spaced apart from the n-type conductivity channel layer and being electrically coupled to the source region;
• and
• an n-type conductivity region extending on the p-type conductivity region beneath the source region and extending toward the drain region without extending beyond the end of the p-type conductivity region.