Germanium-on-insulator substrate and method for forming the same

A germanium-on-insulator substrate comprising:

• a bulk silicon substrate;
• an oxide film disposed on the bulk silicon substrate and having a first region exposing a portion of the bulk silicon substrate and a second region recessed toward the bulk silicon substrate;
• a silicon layer covering a portion of a top surface of the oxide film;
• a germanium layer grown onto the oxide film using the bulk silicon substrate exposed through the first region as a seed layer;
• and
• an insulating layer disposed on the silicon layer,
• wherein the germanium layer contacts the silicon layer.

A method for forming a germanium-on-insulator substrate, the method comprising:

• stacking an oxide film and a silicon layer in sequence on the bulk silicon substrate;
• etching a portion of the silicon layer to expose a portion of the oxide film;
• forming an insulating layer covering both the silicon layer and the exposed oxide film;
• etching a portion of the insulating layer to expose a top surface of the oxide film;
• etching the oxide film to expose a portion of the bulk silicon substrate;
• and
• forming a germanium layer grown from the exposed bulk silicon substrate and disposed on the oxide film.