A junction field effect transistor (JFET) comprises an insulating carrier substrate, a base semiconductor substrate formed on the insulating carrier substrate and a gate region formed on the base semiconductor substrate. The gate region forms a junction with the base semiconductor substrate. The JFET further comprises a first source/drain region formed on the base semiconductor substrate and located on a first side of the gate region and a second source/drain region formed on the base semiconductor substrate and located on a second side of the gate region. A gate stack is deposited on the gate region, a first source/drain stack is deposited on the first source/drain region and a second source/drain stack is deposited on the second source/drain region. At least one of the gate stack, first source/drain stack and second source/drain stack overlaps onto another one of the gate stack, first source/drain stack and second source/drain stack.

A film formation is performed using a target in which a material which is volatilized more easily than gallium when heated at 400 C. to 700 C., such as zinc, is added to gallium oxide by a sputtering method with high mass-productivity which can be applied to a large-area substrate, such as a DC sputtering method or a pulsed DC sputtering method. This film is heated at 400 C. to 700 C., whereby the added material is segregated in the vicinity of a surface of the film. Another portion of the film has a decreased concentration of the added material and a sufficiently high insulating property; therefore, it can be used for a gate insulator of a semiconductor device, or the like.

Disclosed is a semiconductor device having a memory cell which comprises a transistor having a control gate and a storage gate. The storage gate comprises an oxide semiconductor and is able to be a conductor and an insulator depending on the potential of the storage gate and the potential of the control gate. Data is written by setting the potential of the control gate to allow the storage gate to be a conductor, supplying a potential of data to be stored to the storage gate, and setting the potential of the control gate to allow the storage gate to be an insulator. Data is read by supplying a potential for reading to a read signal line connected to one of a source and a drain of the transistor and detecting the change in potential of a bit line connected to the other of the source and the drain.

A method of manufacturing a substrate includes: irradiating, along a first path, a laser beam emitted from a source onto a substrate, wherein the substrate includes a target layer of the laser beam, and wherein the substrate is disposed on a stage; and irradiating, along a second path, a portion the laser beam, which was emitted from the source and reached the target layer, by reflecting the laser beam back onto the target layer using a reflection mirror. An area of a second region of the target layer is greater than an area of a first region of the target layer, wherein the laser beam is irradiated along the second path in the second region, and the laser beam is irradiated along the first path in the first region.

At least one of a plurality of transistors which are highly integrated in an element is provided with a back gate without increasing the number of manufacturing steps. In an element including a plurality of transistors which are longitudinally stacked, at least a transistor in an upper portion includes a metal oxide having semiconductor characteristics, a same layer as a gate electrode of a transistor in a lower portion is provided to overlap with a channel formation region of the transistor in an upper portion, and part of the same layer as the gate electrode functions as a back gate of the transistor in an upper portion. The transistor in a lower portion which is covered with an insulating layer is subjected to planarization treatment, whereby the gate electrode is exposed and connected to a layer functioning as source and drain electrodes of the transistor in an upper portion.

A semiconductor device includes a semiconductor substrate and a p-doped layer formed on the substrate having a dislocation density exceeding 10 cm.sup.2. An n-type layer is formed on or in the p-doped layer. The n-type layer includes a II-VI material configured to tolerate the dislocation density to form an electronic device with reduced leakage current over a device with a III-V n-type layer.

A manufacturing method of a thin film transistor array panel according to an exemplary embodiment of the present invention includes forming an amorphous silicon thin film on a substrate. A lower region of the amorphous silicon thin film is crystallized to form a polycrystalline silicon thin film by irradiating a laser beam with an energy density of from about 150 mj/cm.sup.2 to about 250 mj/cm.sup.2 to the amorphous silicon thin film.

According to one embodiment, a field-effect transistor includes a source region of a first conductivity type, a drain region of the first conductivity type and a channel region of the first conductivity type between the source region and the drain region, the source region, the drain region and the channel region being disposed in a polycrystalline semiconductor layer; a first layer including an amorphous semiconductor layer disposed on the channel region; a gate insulating layer disposed on the first layer; and a gate electrode disposed on the gate insulating layer.

A junction field-effect transistor (JFET) with a gate region that includes two separate sub-regions having material of different conductivity types and/or a Schottky junction that substantially suppresses gate current when the gate junction is forward-biased, as well as complementary circuits that incorporate such JFET devices.

An object is to improve reliability of a semiconductor device. A semiconductor device including a driver circuit portion and a display portion (also referred to as a pixel portion) over the same substrate is provided. The driver circuit portion and the display portion include thin film transistors in which a semiconductor layer includes an oxide semiconductor; a first wiring; and a second wiring. The thin film transistors each include a source electrode layer and a drain electrode layer. In the thin film transistor in the driver circuit portion, the semiconductor layer is sandwiched between a gate electrode layer and a conductive layer. The first wiring and the second wiring are electrically connected to each other in an opening provided in a gate insulating film through an oxide conductive layer.