A semiconductor device includes a channel layer configured to include a first nitride semiconductor containing gallium (Ga) and a first crystal dislocation density, and a barrier layer provided over a first surface side of the channel layer, and configured to include a second nitride semiconductor containing aluminum (Al) and a second crystal dislocation density, wherein the second crystal dislocation density is larger than the first crystal dislocation density.

The present disclosure relates to use of 193-nm excimer laser-based lift-off (LLO) of Al.sub.0.26Ga.sub.0.74N/GaN High-electron mobility transistors (HEMTs) with thick (t>10 μm) AlN heat spreading buffer layers grown over sapphire substrates. The use of the thick AlN heat spreading layer resulted in thermal resistance (R.sub.th) of 16 Kmm/W for as-fabricated devices on sapphire, which is lower than the value of ≈25-50 Kmm/W for standard HEMT structures on sapphire without the heat-spreaders. Soldering the LLO devices onto a copper heat sink led to a further reduction of R.sub.th to 8 Kmm/W, a value comparable to published measurements on bulk SiC substrates. The reduction in R.sub.th by LLO and bonding to copper led to significantly reduced self-heating and drain current droop. A drain current density as high as 0.9 A/mm was observed despite a marginal reduction of the carrier mobility (≈1800 to ≈1500 cm.sup.2/Vs). This is the highest drain current density and mobility reported to-date for LLO AlGaN/GaN HEMTs.

The present disclosure relates to use of 193-nm excimer laser-based lift-off (LLO) of Al.sub.0.26Ga.sub.0.74N/GaN High-electron mobility transistors (HEMTs) with thick (t>10 μm) AlN heat spreading buffer layers grown over sapphire substrates. The use of the thick AlN heat spreading layer resulted in thermal resistance (R.sub.th) of 16 Kmm/W for as-fabricated devices on sapphire, which is lower than the value of ≈25-50 Kmm/W for standard HEMT structures on sapphire without the heat-spreaders. Soldering the LLO devices onto a copper heat sink led to a further reduction of R.sub.th to 8 Kmm/W, a value comparable to published measurements on bulk SiC substrates. The reduction in R.sub.th by LLO and bonding to copper led to significantly reduced self-heating and drain current droop. A drain current density as high as 0.9 A/mm was observed despite a marginal reduction of the carrier mobility (≈1800 to ≈1500 cm.sup.2/Vs). This is the highest drain current density and mobility reported to-date for LLO AlGaN/GaN HEMTs.

Wafers including a diamond layer and a semiconductor layer having III-Nitride compounds and methods for fabricating the wafers are provided. A nucleation layer, at least one semiconductor layer having III-Nitride compound and a protection layer are formed on a silicon substrate. Then, a silicon carrier wafer is glass bonded to the protection layer. Subsequently the silicon substrate, nucleation layer and a portion of the semiconductor layer are removed. Then, an intermediate layer, a seed layer and a first diamond layer are sequentially deposited on the III-Nitride layer. Next, the silicon carrier wafer and the protection layer are removed. Then, a silicon substrate wafer that includes a protection layer, silicon substrate and a diamond layer is prepared and glass bonded to the first diamond layer.

Wafers including a diamond layer and a semiconductor layer having III-Nitride compounds and methods for fabricating the wafers are provided. A nucleation layer, at least one semiconductor layer having III-Nitride compound and a protection layer are formed on a silicon substrate. Then, a silicon carrier wafer is glass bonded to the protection layer. Subsequently the silicon substrate, nucleation layer and a portion of the semiconductor layer are removed. Then, an intermediate layer, a seed layer and a first diamond layer are sequentially deposited on the III-Nitride layer. Next, the silicon carrier wafer and the protection layer are removed. Then, a silicon substrate wafer that includes a protection layer, silicon substrate and a diamond layer is prepared and glass bonded to the first diamond layer.

A heterojunction bipolar transistor includes a collector layer, a base layer, and an emitter layer that are stacked on a substrate. The collector layer includes a graded semiconductor layer in which an electron affinity increases from a side closer to the base layer toward a side farther from the base layer. An electron affinity of the base layer at an interface closer to the collector layer is equal to an electron affinity of the graded semiconductor layer at an interface closer to the base layer.

A heterojunction bipolar transistor includes a collector layer, a base layer, and an emitter layer that are stacked on a substrate. The collector layer includes a graded semiconductor layer in which an electron affinity increases from a side closer to the base layer toward a side farther from the base layer. An electron affinity of the base layer at an interface closer to the collector layer is equal to an electron affinity of the graded semiconductor layer at an interface closer to the base layer.

This application provides a gallium nitride component and a drive circuit thereof. The gallium nitride component includes: a substrate; a gallium nitride (GaN) buffer layer formed on the substrate; an aluminum gallium nitride (AlGaN) barrier layer formed on the GaN buffer layer; and a source, a drain, and a gate formed on the AlGaN barrier layer. The gate includes a P-doped gallium nitride (P—GaN) cap layer formed on the AlGaN barrier layer, and a first gate metal and a second gate metal formed on the P—GaN cap layer. A Schottky contact is formed between the first gate metal and the P—GaN cap layer, and an ohmic contact is formed between the second gate metal and the P—GaN cap layer. In the technical solution provided in this application, the gallium nitride component is a normally-off component, and is conducive to design of a drive circuit.

This application provides a gallium nitride component and a drive circuit thereof. The gallium nitride component includes: a substrate; a gallium nitride (GaN) buffer layer formed on the substrate; an aluminum gallium nitride (AlGaN) barrier layer formed on the GaN buffer layer; and a source, a drain, and a gate formed on the AlGaN barrier layer. The gate includes a P-doped gallium nitride (P—GaN) cap layer formed on the AlGaN barrier layer, and a first gate metal and a second gate metal formed on the P—GaN cap layer. A Schottky contact is formed between the first gate metal and the P—GaN cap layer, and an ohmic contact is formed between the second gate metal and the P—GaN cap layer. In the technical solution provided in this application, the gallium nitride component is a normally-off component, and is conducive to design of a drive circuit.

A semiconductor device includes a plurality of tunnel diodes, each of which includes a first semiconductor region of a first conductive type and a second semiconductor region of a second conductive type that is provided above the first semiconductor region, the second semiconductor region being a nanowire shape; an insulating film provided around a side surface of the second semiconductor region; a plurality of first electrodes, each coupled to the first semiconductor region; and a plurality of second electrodes, each coupled to the second semiconductor region, wherein the second electrode has a first surface that faces the side surface of the second semiconductor region across the insulating film, and a diameter of a second semiconductor region of a first tunnel diode of the plurality of tunnel diodes is different from a diameter of a second semiconductor region of a second tunnel diode.