Image sensor

An image sensor comprising:

• a substrate including a first surface and a second surface opposed to each other, the substrate including a photodiode region;
• a gate electrode on the photodiode region, a lower portion of the gate electrode being extended into the substrate, and an upper portion of the gate electrode being disposed on the first surface of the substrate;
• a first two-dimensional insulating layer between the gate electrode and the substrate;
• a floating diffusion region on the photodiode region and on a side of the gate electrode;
• a two-dimensional channel layer extending from a lowermost surface of the first two-dimensional insulating layer onto an upper surface of the floating diffusion region;
• a second two-dimensional insulating layer between the two-dimensional channel layer and the substrate;
• a two-dimensional buffer layer provided to an upper portion and a lower portion of the two-dimensional channel layer on the floating diffusion region;
• and
• a contact plug in contact with the two-dimensional buffer layer,
• wherein the first and second two-dimensional insulating layers include an insulating material having a two-dimensional crystal structure.

An image sensor comprising:

• a substrate including a first surface and a second surface opposed to each other, the substrate having a first trench recessed from the first surface of the substrate;
• a shallow element isolation pattern in the first trench;
• a deep element isolation pattern in the substrate, the deep element isolation pattern defining a pixel region;
• a photodiode region in the substrate;
• a gate electrode on the photodiode region;
• a gate dielectric layer under the gate electrode;
• a channel region between the gate dielectric layer and the photodiode region;
• a floating diffusion region on the photodiode region and on a side of the gate electrode;
• a contact plug on the first surface of the substrate and electrically connected to the floating diffusion region;
• a micro-lens on the second surface of the substrate;
• and
• color filters between the substrate and the micro-lens,
• wherein the channel region includes:
• a first channel region under the gate dielectric layer;
• and
• a second channel region under the first channel region,
• wherein the first channel region includes a two-dimensional channel layer that includes a TMD material,
• the second channel region includes a silicon channel layer, and
• the two-dimensional channel layer has a stepped structure, and the silicon channel layer has a structure with bends.