A semiconductor device includes a first layer that includes a first semiconductor material disposed on a semiconductor substrate, and a second layer of a second semiconductor material disposed on the first layer. The semiconductor substrate includes Si. The first semiconductor material and the second semiconductor material are different. The second semiconductor material is formed of an alloy including a first element and Sn. A surface region of an end portion of the second layer at both ends of the second layer has a higher concentration of Sn than an internal region of the end portion of the second layer. The surface region surrounds the internal region.

A memory and a method for preparing a memory are provided. The method for preparing the memory includes: providing a substrate, in which the substrate includes a first N-type active region and a first P-type active region; forming an epitaxial layer covering the first P-type active region, in which the epitaxial layer exposes the first N-type active region; simultaneously forming a first gate dielectric layer covering the first N-type active region and a second gate dielectric layer covering the epitaxial layer, in which a thickness of the first gate dielectric layer is substantially the same as a thickness of the second gate dielectric layer; forming a first gate covering the first gate dielectric layer to form a first N-channel Metal Oxide Semiconductor (NMOS) device; and forming a second gate covering the second gate dielectric layer to form a first P-channel Metal Oxide Semiconductor (PMOS) device.

A thin film transistor (TFT) structure. In an example, the TFT includes a gate electrode, a first layer comprising an oxide semiconductor material, and a second layer between the first layer and the gate electrode. The second layer is crystalline and is in contact with the first layer, and includes zirconium and oxygen. The TFT includes a first contact coupled to the first layer at a first location, and a second contact coupled to the first layer at a second location. In some cases, the second layer further includes hafnium. In some cases, the TFT includes a third layer between of the gate electrode and the second layer, the third layer comprising a metal and oxygen. The gate electrode may also include the metal. In some cases, hydrogen is present at an interface between the gate electrode and the second layer.

A method for fabricating a semiconductor device includes receiving a silicon substrate having an isolation feature disposed on the substrate and a well adjacent the isolation feature, wherein the well includes a first dopant. The method also includes etching a recess to remove a portion of the well and epitaxially growing a silicon layer (EPI layer) in the recess to form a channel, wherein the channel includes a second dopant. The method also includes forming a barrier layer between the well and the EPI layer, the barrier layer including at least one of either silicon carbon or silicon oxide. The barrier layer can be formed either before or after the channel. The method further includes forming a gate electrode disposed over the channel and forming a source and drain in the well.