High speed composite p-channel Si/SiGe heterostructure for field effect devices

A layered structure for forming p-channel field effect transistors comprising:

• a single crystalline substrate,
• a first layer of relaxed Si1−xGex formed epitaxially on said substrate where Ge fraction x is in the range from 0.35 to 0.5,
• a second layer of Si1−xGex formed epitaxially on said first layer,
• a third layer of undoped Si formed epitaxially on said second layer,
• a fourth layer of Ge formed epitaxially on said third layer whereby said fourth layer is under compressive strain and having a thickness less than its critical thickness with respect to said first layer,
• a fifth layer of Si1wGew formed epitaxially on said fourth layer wherein the Ge fraction w is in the range from 0.5 to <1.0 and where w−x >0.2 whereby said fifth layer is under compressive strain, and
• a sixth layer of Si1−xGex formed epitaxially on said fifth layer.

A layered structure for forming p-channel field effect transistors comprising:

• a single crystalline substrate,
• a first layer of relaxed Si1−xGex formed epitaxially on said substrate where Ge fraction x is the range from 0.35 to 0.5,
• a second layer of Ge formed epitaxially on said first layer whereby said second layer is under compressive strain and having a thickness less than its critical thickness with respect to said first layer,
• a third layer of Si1−wGew formed epitaxially on said second layer where the Ge fraction w is in the range from 0.5 to <1.0 and where w−x >0.2 whereby said third layer is under compressive strain,
• a fourth layer of undoped Si1−xGex formed epitaxially on said third layer,
• a fifth layer of undoped Si formed epitaxially on said fourth layer, and a sixth layer of p-doped Si1−xGex formed epitaxially on said fifth layer.

A layered structure for forming p-channel field effect transistors comprising:

• a single crystalline substrate,
• a first layer of relaxed Si1−xGex formed epitaxially on said substrate where Ge fraction x is the range from 0.35 to 0.5,
• a second layer of Ge formed epitaxially on said first layer whereby said second layer is under compressive strain and has a thickness less than its critical thickness with respect to said first layer,
• a third layer of Si1−wGew formed epitaxially on said second layer where the Ge fraction w is in the range from 0.5 to <1.0 and where w−x >0.2 whereby said third layer is under compressive strain,
• a fourth layer of undoped Si1−xGex formed epitaxially on said third layer, and
• a fifth layer of p-doped Si1−xGex formed epitaxially on said fourth layer.