Zram heterochannel memory

A method of forming a semiconductor structure, comprising:

• forming a sacrificial gate on a layer of silicon;
• forming trenches in the layer of silicon;
• forming silicon-germanium islands in the trenches;
• forming a mask on the silicon-germanium islands;
• removing the sacrificial gate to form a gate trench defined by the mask;
• forming a channel region in a portion of the layer of silicon exposed by the gate trench;
• forming a gate dielectric and a gate electrode over the channel region and in the gate trench;
• removing the mask;
• forming gate spacers that mask first portions of the silicon-germanium islands;
• forming source/drain regions in second portions of the silicon-germanium islands;
• and
• annealing the structure to cause atoms to migrate from the channel region and the source/drain regions into the first portions of the silicon-germanium islands.

A semiconductor structure, comprising:

• a channel region composed of a first material doped with a first type of impurity;
• source/drain regions composed of a second material doped with a second type of impurity different than the first type of impurity, wherein the second material has a smaller bandgap than the first material;
• lightly doped regions between the channel region and the source/drain regions, wherein the lightly doped regions are composed of the second material;
• and
• a gate over the channel region, wherein the second material extends under edges of the gate.