Transistors with channels formed of low-dimensional materials and method forming same

A device comprising:

• a plurality of dielectric layers;
• a plurality of semiconductor layers, wherein the plurality of dielectric layers and the plurality of semiconductor layers are stacked as a multi-layer stack, and are located alternatingly;
• a gate dielectric contacting first portions of first edges of the plurality of semiconductor layers;
• a gate electrode on the gate dielectric;
• and
• a source/drain contact contacting second portions of the first edges of the plurality of semiconductor layers.

A device comprising:

• an isolation layer;
• a first carbon nanotube layer over the isolation layer;
• a second carbon nanotube layer overlapping the first carbon nanotube layer, wherein the second carbon nanotube layer is vertically spaced apart from the first carbon nanotube layer;
• a gate dielectric comprising:
• a top portion overlapping a first portion of the second carbon nanotube layer;
• and
• sidewall portions physically contacting sidewalls of a first portion of the first carbon nanotube layer and the first portion of the second carbon nanotube layer;
• a gate electrode on the gate dielectric;
• and
• a gate spacer on the gate dielectric, wherein the gate spacer comprises portions on opposite sides of, and are at same levels as, the first carbon nanotube layer and the second carbon nanotube layer.