US Patent 7648853 Dual channel heterostructure

Dual channel heterostructures comprising strained Si and strained Ge-containing layers are disclosed, along with methods for producing such structures. In preferred embodiments, a strain-relaxed buffer layer is deposited on a carrier substrate, a strained Si layer is deposited over the strain-relaxed buffer layer and a strained Ge-containing layer is deposited over the strained Si layer. The structure can be transferred to a host substrate to produce the strained Si layer over the strained Ge-containing layer. By depositing the Si layer first, the process avoids Ge agglomeration problems.