A multi-gate semiconductor device is formed including a semiconductor substrate. The multi-gate semiconductor device also includes a first transistor including a first fin portion extending above the semiconductor substrate. The first transistor has a first channel region formed therein. The first channel region includes a first channel region portion doped at a first concentration of a first dopant type and a second channel region portion doped at a second concentration of the first dopant type. The second concentration is higher than the first concentration. The first transistor further includes a first gate electrode layer formed over the first channel region. The first gate electrode layer may be of a second dopant type. The first dopant type may be N-type and the second dopant type may be P-type. The second channel region portion may be formed over the first channel region portion.