Abstract: The present invention provides a semiconductor device having such a structure formed by sequentially laminating a lower barrier layer composed of lattice-relaxed AlxGa1-xN (0?x?1), a channel layer composed of InyGa1-yN (0?y?1) with compressive strain and a contact layer composed of AlzGa1-zN (0?z?1), wherein a two-dimensional electron gas is produced in the vicinity of an interface of said InyGa1-yN channel layer with said AlzGa1-zN contact layer; a gate electrode is formed so as to be embedded in the recessed portion with intervention of an insulating film, which recessed portion is formed by removing a part of said AlzGa1-zN contact layer by etching it away until said InyGa1-yN channel layer is exposed; and, ohmic electrodes are formed on the AlzGa1-zN contact layer. Thus, the semiconductor device has superior uniformity and reproducibility of the threshold voltage while maintaining a low gate leakage current, and is also applicable to the enhancement mode type.

Abstract: According to one embodiment, a valid-cluster search module searches valid clusters included in first blocks, in each of channels, for compaction. A read command generator generates read commands used to read, in parallel, valid clusters to be migrated to a second block. The valid clusters searched in each of the channels comprise the valid clusters to be migrated. The valid clusters to be migrated correspond to a number of clusters simultaneously written to the second block and to a second number of channels in a first number of channels. A determination module determines the second number of channels corresponding to read commands to be generated next based on a situation of issuance of the read commands.

Abstract: Provided is a semiconductor device capable of suppressing an occurrence of a punch-through phenomenon. A semiconductor device includes a substrate 1, a first n-type semiconductor layer 2, a p-type semiconductor layer 3, a second n-type semiconductor layer 4, a drain electrode 13, a source electrode 11, a gate electrode 12, and a gate insulation film 21, wherein the first n-type semiconductor layer 2, the p-type semiconductor layer 3, and the second n-type semiconductor layer 4 are laminated on the substrate 1 in this order. The drain electrode 13 is in ohmic-contact with the first n-type semiconductor layer 2. The source electrode 11 is in ohmic-contact with the second n-type semiconductor layer 4. An opening portion to be filled or a notched portion that extends from an upper surface of the second n-type semiconductor layer 4 to an upper part of the first n-type semiconductor layer 2 is formed at a part of the p-type semiconductor layer 3 and a part of the second n-type semiconductor layer 4.

Abstract: According to one embodiment, a memory system includes a NAND-type flash memory and a memory controller. The memory controller includes a monitoring module and a determination module. The monitoring module acquires an elapsed time from the start of data erase of a first block in the NAND-type flash memory. The determination module determines whether the elapsed time has exceeded a reference time before completion of the data write in the first block.

Abstract: According to one embodiment, a data storage apparatus comprises a first controller, a second controller, and a third controller. The first controller controls first write processing of writing data to a flash memory in accordance with a request from a host. The second controller controls second write processing of writing data to the flash memory, the second write processing is different from the first write processing.

Abstract: According to one embodiment, a data storage device includes a first controller, a second controller, and a third controller. The first controller performs a control operation of writing data of a first data unit to a storage area in a flash memory and reading the data of the first data unit from the storage area. The second controller carries out migration processing of measuring a data amount of valid data stored in storage areas of a second data unit that is a data erase processing unit.

Abstract: The reliability of a field effect transistor made of a nitride semiconductor material is improved. An ohmic electrode includes a plurality of unit electrodes isolated to be separated from each other. With this configuration, an on-state current can be prevented from flowing in the unit electrodes in a y-axial direction (negative direction). Further, in the respective unit electrodes, a current density of the on-state current flowing in the y-axial direction (negative direction) can be prevented from increasing. As a result, an electromigration resistance of the ohmic electrode can be improved.

Abstract: According to one embodiment, a data storage apparatus comprises a first controller, a second controller, a third controller, and a fourth controller. The first controller controls a flash memory, writing and reading data, in units of blocks, to and from the flash memory. The second controller detects any a write-interrupted block is interrupted by the first controller. The third controller sets the write-interrupted block detected by the second controller, as a block to be refreshed in another block. The fourth controller performs the process of refreshing.

Abstract: A field effect transistor includes a nitride-based semiconductor multi-layer structure, a source electrode (108), a drain electrode (109), a protective film (110), and a gate electrode (112) that is provided in a recess structure, which is formed by etching, directly or with a gate insulating film interposed therebetween. The nitride-based semiconductor multi-layer structure includes at least a base layer (103) made of AlXGa1-XN (0?1), a channel layer (104) made of GaN or InGaN, a first electron supply layer (105), which is an undoped or n-type AlYGa1-YN layer, a threshold value control layer (106), which is an undoped AlZGa1-ZN layer, and a second electron supply layer (107), which is an undoped or n-type AlWGa1-WN layer, epitaxially grown in this order on a substrate (101) with a buffer layer (102) interposed therebetween. The Al composition of each layer in the nitride-based semiconductor multi-layer structure satisfies 0<X?Y?1 and 0<Z?Y?1.

Abstract: According to one embodiment, a storage controller includes a condition storage, a determination module, a wear-leveling block retainer, and a data transfer controller. The condition storage is provided in a storage including a plurality of blocks, and stores block condition information including at least one of erasure time information indicating when data is erased last time and erasure count information indicating the number of times data is erased. The determination module determines whether there is a block that requires wear leveling based on the block condition information. The wear-leveling block retainer retains block identification information that identifies a block determined to require wear leveling. The data transfer controller performs compaction to transfer data stored in blocks of the storage for collecting the data in a block, and, when the block identification information is retained, transfers data stored in the block identified by the block identification information.

Abstract: There is provided a semiconductor apparatus capable of achieving both a reverse blocking characteristic and a low on-resistance. The semiconductor apparatus includes a first semiconductor layer including a channel layer, a source electrode formed on the first semiconductor layer, a drain electrode formed at a distance from the source electrode on the first semiconductor layer, and a gate electrode formed between the source electrode and the drain electrode on the first semiconductor layer. The drain electrode includes a first drain region where reverse current between the first semiconductor layer and the first drain region is blocked, and a second drain region formed at a greater distance from the gate electrode than the first drain region, where a resistance between the first semiconductor layer and the second drain region is lower than a resistance between the first semiconductor layer and the first drain region.

Abstract: A semiconductor device includes a channel layer, an electron-supplying layer provided on the channel layer, a cap layer provided on the electron-supplying layer and creating lattice match with the channel layer, and ohmic electrodes provided on the cap layer. The cap layer has a composition of (InyAl1-y)zGa1-zN (0?y?1, 0?z?1). The z for such cap layer monotonically decreases as being farther away from the electron-supplying layer.

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: A semiconductor device includes a semiconductor element having a rectangular two-dimensional geometry and serving as a heat source, a first heat sink section including the semiconductor element mounted thereon, and a second heat sink section joined to an opposite side of the first heat sink section that includes the semiconductor element. A relation among directional components of thermal conductivity is K1yy?K1xx>K1zz, where directional components of a three-dimensional thermal conductivity of the heat sink section in X, Y, and Z directions are determined as Kxx, Kyy, and Kzz. A relation among directional components of a thermal conductivity of the second heat sink section is K2zz?K2yy>K2xx or K2yy?K2zz>K2xx, where the directional components of the thermal conductivity of the second heat sink section in X, Y, and X directions are determined as K2xx, K2yy, and K2zz.

Abstract: Disclosed is an HJFET 110 which comprises: a channel layer 12 composed of InyGa1-yN (0?y?1); a carrier supply layer 13 composed of AlxGa1-xN (0?x?1), the carrier supply layer 13 being provided over the channel layer 12 and including at least one p-type layer; and a source electrode 15S, a drain electrode 15D and a gate electrode 17 which are disposed facing the channel layer 12 through the p-type layer, and provided over the carrier supply layer 13. The following relational expression is satisfied: 5.6×1011x<NA×?×t [cm?2]<5.6×1013x, where x denotes an Al compositional ratio of said carrier supply layer, t denotes a thickness of said p-type layer, NA denotes an impurity concentration, and ? denotes an activation ratio.

Abstract: 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: A semiconductor device capable of suppressing the occurrence of a punch-through phenomenon is provided. A first n-type conductive layer (2?) is formed on a substrate (1?). A p-type conductive layer (3?) is formed thereon. A second n-type conductive layer (4?) is formed thereon. On the under surface of the substrate (1?), there is a drain electrode (13?) connected to the first n-type conductive layer (2?). On the upper surface of the substrate (1?), there is a source electrode (11?) in ohmic contact with the second n-type conductive layer (4?), and a gate electrode (12?) in contact with the first n-type conductive layer (2?), p-type conductive layer (3?), the second n-type conductive layer (4?) through an insulation film (21?). The gate electrode (12?) and the source electrode (11?) are alternately arranged. The p-type conductive layer (3?) includes In.

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 includes: a substrate; a collector and a base layer with a p-conductive-type, an emitter layer with an n-conductive-type. The collector layer is formed above the substrate and includes a first nitride semiconductor. The base layer with the p-conductive-type is formed on the collector layer and includes a second nit ride semiconductor. The emitter layer with the n-conductive-type is formed on the base layer and includes a third nitride semiconductor. The collector layer, the base layer and the emitter layer are formed so that crystal growing directions with respect to a surface of the substrate are in parallel to a [0001] direction of the substrate. The first nitride semiconductor includes: InycAlxcGa1-xc-ycN (0?xc?1, 0?yc?1, 0<xc+yc?1). In the first nitride semiconductor, a length of an a-axis on a surface side is longer than a length of an a-axis on a substrate side.

Abstract: A semiconductor device includes: a first nitride semiconductor layer; a second nitride semiconductor layer formed over the first nitride semiconductor layer; and a gate electrode facing the second nitride semiconductor layer via a gate insulating film. Because the second nitride semiconductor layer is formed by stacking plural semiconductor layers with their Al composition ratios different from each other, the Al composition ratio of the second nitride semiconductor layer changes stepwise. The semiconductor layers forming the second nitride semiconductor layer are polarized in the same direction so that, among the semiconductor layers, a semiconductor layer nearer to the gate electrode has higher (or lower) intensity of polarization.