“…The on-insulator (''OI'') substrates are generally derived from bulk structures by a combination of epitaxial growth, wafer bonding, and delamination or etch-back methods, which preserve the strain state of the layers. For example, strained silicon directly on insulator (SSDOI), illustrated in Figure 5(e), is derived from biaxial strained Si/relaxed Si 1Àx Ge x by transfer of the epitaxial layers and removal of the relaxed Si 1Àx Ge x virtual substrate, leaving a strained Si layer directly in contact with silicon dioxide [19][20][21]. The on-insulator technologies provide a pathway to implementing mobility enhancement in partially or fully depleted devices, in ultrathin-body MOSFETs, or nonplanar (e.g., doublegate) MOSFETs, and are discussed in the next subsection.…”