Abstract: The characteristics of a semiconductor device are improved. A semiconductor device is formed so as to have a channel layer formed over a substrate, a barrier layer, a trench penetrating through the barrier layer in an opening region, and reaching some point of the channel layer, a gate electrode arranged in the trench via a gate insulation film, and an insulation film formed over the barrier layer outside the opening region. Then, the insulation film has a lamination structure of a Si-rich silicon nitride film, and a N-rich silicon nitride film situated thereunder. Thus, the upper layer of the insulation film is set as the Si-rich silicon nitride film. This enables the improvement of the breakdown voltage, and further, enables the improvement of the etching resistance. Whereas, the lower layer of the insulation film is set as the N-rich silicon nitride film. This can suppress collapse.

Abstract: A semiconductor device including a first nitride semiconductor layer formed over a substrate, a second nitride semiconductor layer formed on the first nitride semiconductor layer and having a band gap wider than that of the first nitride semiconductor layer, a trench penetrating through the second nitride semiconductor layer to reach the middle of the first nitride semiconductor layer, a conductive film formed at a corner portion corresponding to an end portion of a bottom surface of the trench and a gate electrode disposed via a gate insulating film inside the trench including a region on the conductive film.

Abstract: Provided is a semiconductor device in which the trade-off between the withstand voltage and the on-resistance is improved and the performance is increased. A semiconductor device comprises a substrate 1, a first n-type semiconductor layer 21?, a second n-type semiconductor layer 23, a p-type semiconductor layer 24, and a third n-type semiconductor layer 25?, wherein the first n-type semiconductor layer 21?, the second n-type semiconductor layer 23, the p-type semiconductor layer 24, and the third n-type semiconductor layer 25? are laminated at the upper side of the substrate 1 in this order. The drain electrode 13 is in ohmic-contact with the first n-type semiconductor layer 21? and the source electrode 12 is in ohmic-contact with the third n-type semiconductor layer 25?.

Abstract: The reliability of a power MISFET made of a nitride semiconductor material is improved. A strain relaxation film is disposed between a polyimide film and a gate electrode, to suppress a stress exerted on an electron supply layer and a channel layer from the polyimide film, and suppress a stress strain generated in the electron supply layer and the channel layer. As a result, a change in channel electron concentration in the channel layer is suppressed to prevent a threshold voltage or an on-resistance of the power MISFET from fluctuating.

Abstract: A semiconductor device includes a buffer layer, a channel layer and a barrier layer formed over a substrate, a trench penetrating through the barrier layer to reach the middle of the channel layer, and a gate electrode disposed inside the trench via a gate insulating film. The channel layer contains n-type impurities, and a region of the channel layer positioned on a buffer layer side has an n-type impurity concentration larger than a region of the channel layer positioned on a barrier layer side, and the buffer layer is made of nitride semiconductor having a band gap wider than that of the channel layer. The channel layer is made of GaN and the buffer layer is made of AlGaN. The channel layer has a channel lower layer containing n-type impurities at an intermediate concentration and a main channel layer formed thereon and containing n-type impurities at a low concentration.

Abstract: An electrode comes in ohmic contact with an AlGaN layer. A semiconductor device SD has a nitride semiconductor layer GN2, and an AlxGa(1?x)N layer AGN (hereinafter referred to as “AlGaN layer AGN), and Al electrodes DE, SE. in the AlGaN layer AGN, 0<X?0.2 is satisfied. Also, both of a concentration of a p-type impurity and a concentration of an n-type impurity in the AlGaN layer AGN are 1×1016 cm?3 or lower. In this example, the p-type impurity is exemplified by, for example, Be, C, and Mg, and the n-type impurity is exemplified by Si, S, and Se. Also, the Al electrodes DE and SE are connected to the AlGaN layer AGN. Because a composition ratio of Al is limited to the above-mentioned range, the Al electrodes DE and SE are brought into ohmic contact with the AlGaN layer AGN.

Abstract: According to one embodiment, a data storage apparatus includes a flash memory and a controller. The controller includes a compaction processor. The compaction processor performs the compaction processing on the flash memory, to dynamically set a range of compaction processing targets based on a number of available blocks and an amount of valid data in each of the blocks, and to search the range of compaction processing targets for blocks each with a relatively small amount of valid data as the target blocks for the compaction processing.

Abstract: In a group III nitride-type field effect transistor, the present invention reduces a leak current component by conduction of residual carriers in a buffer layer, and achieves improvement in a break-down voltage, and enhances a carrier confinement effect (carrier confinement) of a channel to improve pinch-off characteristics (to suppress a short channel effect). For example, when applying the present invention to a GaN-type field effect transistor, besides GaN of a channel layer, a composition-modulated (composition-gradient) AlGaN layer in which aluminum composition reduces toward a top gradually or stepwise is used as a buffer layer (hetero buffer).

Abstract: To provide a semiconductor device having improved characteristics. The semiconductor device has a substrate and thereon a buffer layer, a channel layer, a barrier layer, a trench penetrating therethrough and reaching the inside of the channel layer, a gate electrode placed in the trench via a gate insulating film, and drain and source electrodes on the barrier layer on both sides of the gate electrode. The gate insulating film has a first portion made of a first insulating film and extending from the end portion of the trench to the side of the drain electrode and a second portion made of first and second insulating films and placed on the side of the drain electrode relative to the first portion. The on resistance can be reduced by decreasing the thickness of the first portion at the end portion of the trench on the side of the drain electrode.

Abstract: In a group III nitride-type field effect transistor, the present invention reduces a leak current component by conduction of residual carriers in a buffer layer, and achieves improvement in a break-down voltage, and enhances a carrier confinement effect (carrier confinement) of a channel to improve pinch-off characteristics (to suppress a short channel effect). For example, when applying the present invention to a GaN-type field effect transistor, besides GaN of a channel layer, a composition-modulated (composition-gradient) AlGaN layer in which aluminum composition reduces toward a top gradually or stepwise is used as a buffer layer (hetero buffer).

Abstract: To improve performance of a semiconductor device. For example, on the assumption that a superlattice layer is inserted between a buffer layer and a channel layer, a concentration of acceptors introduced into nitride semiconductor layers forming a part of the superlattice layer is higher than a concentration of acceptors introduced into nitride semiconductor layers forming the other part of the superlattice layer. That is, the concentration of acceptors introduced into the nitride semiconductor layers having a small band gap is higher than the concentration of acceptors introduced into the nitride semiconductor layers having a large band gap.

Abstract: A semiconductor device includes a buffer layer, a channel layer and a barrier layer formed over a substrate, a trench penetrating through the barrier layer to reach the middle of the channel layer, and a gate electrode disposed inside the trench via a gate insulating film. The channel layer contains n-type impurities, and a region of the channel layer positioned on a buffer layer side has an n-type impurity concentration larger than a region of the channel layer positioned on a barrier layer side, and the buffer layer is made of nitride semiconductor having a band gap wider than that of the channel layer. The channel layer is made of GaN and the buffer layer is made of AlGaN. The channel layer has a channel lower layer containing n-type impurities at an intermediate concentration and a main channel layer formed thereon and containing n-type impurities at a low concentration.

Abstract: A method for manufacturing a semiconductor device includes forming a buffer layer made of a nitride semiconductor, forming a channel layer made of a nitride semiconductor over the buffer layer, forming a barrier layer made of a nitride semiconductor over the channel layer, forming a cap layer made of a nitride semiconductor over the barrier layer, forming a gate insulating film so as to in contact with the cap layer; and forming a gate electrode over the gate insulating film, wherein compression strains are generated at an interface between the cap layer and the barrier layer and an interface between the channel layer and the buffer layer and a tensile strain is generated at an interface between the barrier layer and the channel layer by controlling compositions of the cap layer, the barrier layer, the channel layer, and the buffer layer.

Abstract: A semiconductor device includes semiconductor layers, an anode electrode, and a cathode electrode. The semiconductor layers include a composition change layer, the anode electrode is electrically connected to one of principal surfaces of the composition change layer through a formation of a Schottky junction between the anode electrode and a part of the semiconductor layers, the cathode electrode is electrically connected to the other of the principal surfaces of the composition change layer through a formation of a junction between the cathode electrode and another part of the semiconductor layers, the anode electrode and the cathode electrode are capable of applying a voltage to the composition change layer in a direction perpendicular to the principal surface.

Abstract: A first log indicating that a system is running is recorded in a second storage unit before a first difference log is recorded in the second storage unit after system startup, and a second log indicating that the system halts is recorded in the second storage unit following the difference log, at the time of normal system halt, and it is judged whether normal system halt has been performed or an incorrect power-off sequence has been performed last time, based on a recorded state of the first and second logs in the second storage unit, at the time of system startup, thereby detecting an incorrect power-off easily and reliably.

Abstract: Compression strains are generated at an interface between the cap layer and the barrier layer and an interface between the channel layer and the buffer layer and a tensile strain is generated at an interface between the barrier layer and the channel layer. Therefore, negative charge is higher than positive charge at the interface between the cap layer and the barrier layer and the interface between the channel layer and the buffer layer, while positive charge is higher than negative charge at the interface between the barrier layer and the channel. The channel layer has a stacked layer structure of a first layer, a second layer, and a third layer. The second layer has a higher electron affinity than those of the first layer and the third layer.

Abstract: A bipolar transistor is provided with an emitter layer, a base layer and a collector layer. The emitter layer is formed above a substrate and is an n-type conductive layer including a first nitride semiconductor. The base layer is formed on the emitter layer and is a p-type conductive including a second nitride semiconductor. The collector layer is formed on the base layer and includes a third nitride semiconductor. The collector layer, the base layer and the emitter layer are formed such that a crystal growth direction to the substrate surface is parallel to a substrate direction of [000-1]. The third nitride semiconductor contains InycAlxcGa1-xc-ycN (0•xc•1, 0•yc•1, 0<xc+yc•1). The a-axis length on the side of a surface in the third nitride semiconductor is shorter than the a-axis length on the side of the substrate.

Abstract: According to one embodiment, a memory device includes a memory, a memory interface, a command generator, an access command returning module and a command progress manager. The memory interface accesses the memory in parallel in accordance with access commands. The command generator speculatively issues access commands to the memory interface. The access command returning module returns access commands already issued to the memory interface and unexecuted at a time of occurrence of an error, through corresponding purge responses. The command progress manager updates command progress management information such that the command progress management information indicates the oldest one of the unexecuted access commands. The command generator reissues the returned unexecuted access commands to the memory interface based on the updated command progress management information.

Abstract: According to one embodiment, a command generator sequentially and speculatively issues channel-by-channel access commands to a memory interface in a predetermined access process. A purger returns a series of unexecuted already-issued access commands using a purge response if an error occurs in any of memory accesses via a plurality of channels. A command progress manager updates command progress information such that the command progress on each of the plurality of channels returns to a position specified in an oldest access command of a series of the returned access commands issued to the channel. The command generator issues the channel-by-channel access commands including the oldest access command to the memory interface based on the updated command progress information.

Abstract: A heterojunction filed effect transistor with a low access resistance, a low on resistance, and the like, a method for producing a heterojunction filed effect transistor and an electron device are provided.