Semiconductor structure and methods for manufacturing the same

Embodiments provide a semiconductor structure and a method for manufacturing the same. The semiconductor structure includes a substrate having a first region and a second region. The semiconductor structure also includes an epitaxial layer above the substrate. The semiconductor structure also includes a first device on the first region of the substrate, and a second device on the second region of the substrate. The first device includes a first gate electrode, a first source electrode and a first drain electrode disposed at two opposite sides of the first gate electrode, wherein a dielectric layer is disposed on the epitaxial layer and covers the first gate electrode. The second device includes a second gate electrode disposed on the dielectric layer, a second source electrode and a second drain electrode disposed at two opposite sides of the second gate electrode, wherein the second source electrode is electrically connected to the first drain electrode. The semiconductor structure also includes an isolation