Carrier channel with element concentration gradient distribution and fabrication method thereof

A fabricating method of a carrier channel with an element concentration gradient distribution, comprising:

• providing a substrate;
• forming a first isolation layer having a first through hole on the substrate;
• forming a stacking layer on the first isolation layer, wherein the stacking layer is filled into the first through hole and contacts with the substrate;
• forming a second isolation layer on the stacking layer;
• defining a transfer pattern on the second isolation layer by a photolithographic etching process, wherein the second isolation layer having the transfer pattern is a hard mask;
• transferring the transfer pattern onto the stacking layer by a selective etching process and the hard mask;
• forming a third isolation layer on the substrate, wherein the third isolation layer covers the first isolation layer, the stacking layer, and the hard mask;
• and
• executing a rapid melting growth process for crystallizing the stacking layer into the carrier channel from a contact surface between the stacking layer and the substrate, wherein the carrier channel has the element concentration gradient distribution.