Abstract: A nitride-based semiconductor diode includes a substrate, a first semiconductor layer disposed on the substrate, and a second semiconductor layer disposed on the first semiconductor layer. The first and second semiconductor layers include a nitride-based semiconductor. A first portion of the second semiconductor layer may have a thickness thinner than a second portion of the second semiconductor layer. The diode may further include an insulating layer disposed on the second semiconductor layer, a first electrode covering the first portion of the second semiconductor layer and forming an ohmic contact with the first semiconductor layer and the second semiconductor layer, and a second electrode separated from the first electrode, the second electrode forming an ohmic contact with the first semiconductor layer and the second semiconductor layer.

Abstract: A high electron mobility transistor (HEMT) according to example embodiments includes a channel layer, a channel supply layer on the channel layer, a source electrode and a drain electrode on at least one of the channel layer and the channel supply layer, a gate electrode between the source electrode and the drain electrode, and a Schottky electrode forming a Schottky contact with the channel supply layer. An upper surface of the channel supply layer may define a Schottky electrode accommodation unit. At least part of the Schottky electrode may be in the Schottky electrode accommodation unit. The Schottky electrode is electrically connected to the source electrode.

Abstract: According to example embodiments, High electron mobility transistors (HEMTs) may include a discontinuation region in a channel region. The discontinuation region may include a plurality of 2DEG unit regions that are spaced apart from one another. The discontinuation region may be formed at an interface between two semiconductor layers or adjacent to the interface. The discontinuation region may be formed by an uneven structure or a plurality of recess regions or a plurality of ion implantation regions. The plurality of 2DEG unit regions may have a nanoscale structure. The plurality of 2DEG unit regions may be formed in a dot pattern, a stripe pattern, or a staggered pattern.

Abstract: An Enhancement-mode (E-mode) high electron mobility transistor (HEMT) includes a channel layer with a 2-Dimensional Electron Gas (2DEG), a barrier layer inducing the 2DEG in the channel layer, source and drain electrodes on the barrier layer, a depletion layer on the barrier layer between the source and drain electrodes, and a gate electrode on the depletion layer. The barrier layer is recessed below the gate electrode and the depletion layer covers a surface of the recess and extends onto the barrier layer around the recess.

Abstract: A method for forming a selective ohmic contact for a Group III-nitride heterojunction structured device may include forming a conductive layer and a capping layer on an epitaxial substrate including at least one Group III-nitride heterojunction layer and having a defined ohmic contact region, the capping layer being formed on the conductive layer or between the conductive layer and the Group III-nitride heterojunction layer in one of the ohmic contact region and non-ohmic contact region, and applying at least one of a laser annealing process and an induction annealing process on the substrate at a temperature of less than or equal to about 750° C. to complete the selective ohmic contact in the ohmic contact region.

Abstract: According to example embodiments, a high electron mobility transistor (HEMT) includes: stack including a buffer layer, a channel layer containing a two dimensional electron gas (2DEG) channel, and a channel supply layer sequentially stacked on each other, the stack defining a first hole and a second hole that are spaced apart from each other. A first electrode, a second electrode, and third electrode are spaced apart from each other along a first surface of the channel supply layer. A first pad is on the buffer layer and extends through the first hole of the stack to the first electrode. A second pad is on the buffer layer and extends through the second hole of the stack to the second electrode. A third pad is under the stack and electrically connected to the third electrode.

Abstract: Power electronic devices including 2-dimensional electron gas (2DEG) channels and methods of manufacturing the same. A power electronic device includes lower and upper material layers for forming a 2DEG channel, and a gate contacting an upper surface of the upper material layer. A region below the gate of the 2DEG channel is an off region where the density of a 2DEG is reduced or zero. The entire upper material layer may be continuous and may have a uniform thickness. A region of the upper material layer under the gate contains an impurity for reducing or eliminating a lattice constant difference between the lower and upper material layers.

Abstract: Provided is a semiconductor device that may include a switching device having a negative threshold voltage, and a driving unit between a power terminal and a ground terminal and providing a driving voltage for driving the switching device. The switching device may be connected to a virtual ground node having a virtual ground voltage that is greater than a ground voltage supplied from the ground terminal and may be turned on when a difference between the driving voltage and the virtual ground voltage is greater than the negative threshold voltage.

Abstract: According to example embodiments, a substrate structure may include a GaN-based third material layer, a GaN-based second material layer, a GaN-based first material layer, and a buffer layer on a non-GaN-based substrate. The GaN-based first material layer may be doped with a first conductive type impurity. The GaN-based second material layer may be doped with a second conductive type impurity at a density that is less than a density of the first conductive type impurity in the first GaN-based material layer. The GaN-based third material layer may be doped with a first conductive type impurity at a density that is less than the density of the first conductive type impurity of the GaN-based first material layer. After a second substrate is attached onto the substrate structure, the non-GaN-based substrate may be removed and a GaN-based vertical type semiconductor device may be fabricated on the second substrate.

Abstract: According to example embodiments, a high electron mobility transistor (HEMT) includes a channel supply layer and a channel layer. The channel layer may include an effective channel region and a high resistivity region. The effective channel region may be between the high resistivity region and the channel supply layer. The high resistivity region may be a region into which impurities are ion-implanted. According to example embodiments, a method of forming a HEMT includes forming a device unit, including a channel layer and a channel supply layer, on a first substrate; adhering a second substrate to the device unit; removing the first substrate; and forming a high resistivity region by ion-implanting impurities into at least a portion of the channel layer.

Abstract: According to example embodiments a transistor includes a channel layer on a substrate, a first channel supply layer on the channel, a depletion layer, a second channel supply layer, source and drain electrodes on the first channel supply layer, and a gate electrode on the depletion layer. The channel includes a 2DEG channel configured to generate a two-dimensional electron gas and a depletion area. The first channel supply layer corresponds to the 2DEG channel and defines an opening that exposes the depletion area. The depletion layer is on the depletion area of the channel layer. The second channel supply layer is between the depletion layer and the depletion area.

Abstract: High electron mobility transistors (HEMTs) including a substrate and a HEMT stack on the substrate, the HEMT stack including a compound semiconductor layer that includes a 2-dimensional electron gas (2DEG), an upper compound semiconductor layer that has a polarization index higher than a polarization index of the compound semiconductor layer, and a source electrode, a drain electrode, and a gate that are disposed on the upper compound semiconductor layer. The substrate may be a nitride substrate that has a dielectric constant and a thermal conductivity higher than a dielectric constant and a thermal conductivity of a silicon substrate. The substrate may include an insulating layer that has a dielectric constant and a thermal conductivity higher than a dielectric constant and a thermal conductivity of the silicon substrate, a metal layer that is deposited on the insulating layer, and a plate that is attached to the metal layer.

Abstract: High electron mobility transistors (HEMTs) including a cavity below a drain and methods of manufacturing HEMTS including removing a portion of a substrate below a drain.

Abstract: High electron mobility transistors (HEMTs) and methods of manufacturing the same. A HEMT may include a channel layer and a channel supply layer, and the channel supply layer may be a multilayer structure. The channel supply layer may include an etch stop layer and an upper layer on the etch stop layer. A recess region may be in the upper layer. The recess region may be a region recessed to an interface between the upper layer and the etch stop layer. A gate electrode may be on the recess region.

Abstract: A phase change memory device includes a switching device and a storage node connected to the switching device. The storage node includes a bottom stack, a phase change layer disposed on the bottom stack and a top stack disposed on the phase change layer. The phase change layer includes a unit for increasing a path of current flowing through the phase change layer and reducing a volume of a phase change memory region. The area of a surface of the unit disposed opposite to the bottom stack is greater than or equal to the area of a surface of the bottom stack in contact with the phase change layer.

Abstract: A method of manufacturing a High Electron Mobility Transistor (HEMT) may include forming first and second material layers having different lattice constants on a substrate, forming a source, a drain, and a gate on the second material layer, and changing the second material layer between the gate and the drain into a different material layer, or changing a thickness of the second material layer, or forming a p-type semiconductor layer on the second material layer. The change in the second material layer may occur in an entire region of the second material layer between the gate and the drain, or only in a partial region of the second material layer adjacent to the gate. The p-type semiconductor layer may be formed on an entire top surface of the second material layer between the gate and the drain, or only on a partial region of the top surface adjacent to the gate.

Abstract: An Enhancement-mode (E-mode) high electron mobility transistor (HEMT) includes a channel layer with a 2-Dimensional Electron Gas (2DEG), a barrier layer inducing the 2DEG in the channel layer, source and drain electrodes on the barrier layer, a depletion layer on the barrier layer between the source and drain electrodes, and a gate electrode on the depletion layer. The barrier layer is recessed below the gate electrode and the depletion layer covers a surface of the recess and extends onto the barrier layer around the recess.

Abstract: According to an example embodiment, a high electron mobility transistor (HEMT) includes a substrate, a buffer layer on the substrate, a channel layer on the buffer layer, and a barrier structure on the channel layer. The buffer layer includes a 2-dimensional electron gas (2DEG). A polarization of the barrier structure varies in a region corresponding to a gate electrode. The HEMT further includes and the gate electrode, a source electrode, and a drain electrode on the barrier structure.

Abstract: The methods may include forming a first material layer on a substrate, increasing electric resistance of the first material layer, and forming a source pattern and a drain pattern, which are spaced apart from each other, on the first material layer, a band gap of the source and drain patterns greater than a band gap of a first material layer.

Abstract: According to an example embodiment, a power electronic device includes a first semiconductor layer, a second semiconductor layer on a first surface of the first semiconductor layer, and a source, a drain, and a gate on the second semiconductor layer. The source, drain and gate are separate from one another. The power electronic device further includes a 2-dimensional electron gas (2DEG) region at an interface between the first semiconductor layer and the second semiconductor layer, a first insulating layer on the gate and a second insulating layer adjacent to the first insulating layer. The first insulating layer has a first dielectric constant and the second insulating layer has a second dielectric constant less than the first dielectric constant.