A semiconductor structure includes a stacked metal oxide layer on a substrate, wherein the stacked metal oxide layer includes a first metal oxide layer, a second metal oxide layer, and a third metal oxide layer from top to bottom, and the energy bandgap of the second metal oxide layer is lower than the energy bandgap of the first metal oxide layer and that of the third metal oxide layer. The semiconductor structure includes a metal oxide layer on a substrate, wherein the energy bandgap of the metal oxide layer changes along a direction perpendicular to the surface of the substrate. The present invention also provides a semiconductor process forming said semiconductor structure.