Semiconductor structure having a plurality of heterojunction structures stack

A semiconductor structure, comprising:

• a substrate;
• an insulation layer on the substrate;
• a protrusion structure protruding out of the insulation layer, wherein the protrusion structure comprises a source region, a drain region, and a channel region between the source region and the drain region;
• the protrusion structure comprises:
• a first heterojunction structure, a second through an n-th heterojunction structure sequentially stacked along a direction away from the substrate, wherein n is an integer greater than or equal to 2;
• the first heterojunction structure comprises a first channel layer and a first barrier layer, the second heterojunction structure comprises a second channel layer and a second barrier layer, and the n-th heterojunction structure comprises an n-th channel layer and an n-th barrier layer, and at least one of the first barrier layer through the n-th barrier layer is doped with an N-type element;
• a source electrode covered on the source region;
• a drain electrode covered on the drain region;
• and
• a gate structure covered on the channel region;
• wherein at least one of the first barrier layer, the second barrier layer, through the n-th barrier layer comprises a first N-type ion doped region, a second N-type ion doped region, through an m-th N-type ion doped region which are sequentially arranged, wherein m is an integer greater than or equal to 2.