Abstract: The present disclosure describes porous GaN layers and/or compliant substrates used to enable relaxation of previously strained top layers and the deposition of relaxed or partially relaxed on top. Relaxed In GaN layers are fabricated without generation of crystal defects, which can serve as base layers for high performance long wavelength light emitting devices (LEDs, lasers) solar cells, or strain engineered transistors. Similarly, relaxed AlGaN layers can serve as base layers for high performance short wavelength UV light emitting devices (LEDs, lasers) solar cells, or wide bandgap transistors.

Abstract: Described herein are III-N (e.g. GaN) devices having a stepped cap layer over the channel of the device, for which the III-N material is orientated in an N-polar orientation.

Abstract: An optoelectronic or electronic device structure, including an active region on or above a polar substrate, wherein the active region comprises a polar p region. The device structure further includes a hole supply region on or above the active region. Holes in the hole supply region are driven by a field into the active region, the field arising at least in part due to a piezoelectric and/or spontaneous polarization field generated by a composition and grading of the active region.

Abstract: A substrate comprising a III-N base layer comprising a first portion and a second portion, the first portion of the III-N base layer having a first natural lattice constant and a first dislocation density; and a first III-N layer having a second natural lattice constant and a second dislocation density on the III-N base layer, the first III-N layer having a thickness greater than 10 nm. An indium fractional composition of the first III-N layer is greater than 0.1; the second natural lattice constant is at least 1% greater than the first natural lattice constant; a strain-induced lattice constant of the first III-N layer is greater than 1.0055 times the first natural lattice constant; and the second dislocation density is less than 1.5 times the first dislocation density.

Abstract: A method for fabricating a device, as well as the device itself, which includes growing a bonding layer on a first wafer or substrate, wherein the bonding layer includes at least partially relaxed features; and then bonding a second wafer or substrate to the features in on the first wafer or substrate, to cap and contact the features with separately grown material.

Abstract: Strain is used to enhance the properties of p- and n-materials so as to improve the performance of III-N electronic and optoelectronic devices. In one example, transistor devices include a channel aligned along uniaxially strained or relaxed directions of the III-nitride material in the channel. Strain is introduced using buffer layers or source and drain regions of different composition.

Abstract: Derivative cancellation techniques have been used to linearize transistors using multiple discreet devices. However at frequencies approaching and in the mm-wave regime the use of individual devices no longer works due to the parasitics associated with combining the devices. In this invention device structures are described which apply the derivative cancellation technique in a single device thus removing the detrimental impact of combining. In one example, an N-polar transistor structure includes a channel; a cap structure comprising a plurality of cap layers on or above the channel; a source contact and a drain contact to the channel; and a castellated, stepped, or varying pattern formed in the cap layers so that gate metal deposited on the pattern forms at least two different threshold voltages and current combines in the ohmic region with essentially zero parasitic inductance.

Abstract: A novel design for a nitrogen polar high-electron-mobility transistor (HEMT) structure comprising a GaN/InGaN composite channel. As A novel design for a nitrogen polar high-electron-mobility transistor (HEMT) structure comprising a GaN/InGaN composite channel. As illustrated herein, a thin InGaN layer introduced in the channel increases the carrier density, reduces the electric field in the channel, and increases the carrier mobility. The dependence of p on InGaN thickness (tInGaN) and indium composition (xIn) was investigated for different channel thicknesses. With optimized tInGaN and xIn, significant improvements in electron mobility were observed. For a 6 nm channel HEMT, the electron mobility increased from 606 to 1141 cm2/(V·s) when the 6 nm thick pure GaN channel was replaced by the 4 nm GaN/2 nm In0.1Ga0.9N composite channel.

Abstract: Described herein are III-N (e.g. GaN) devices having a stepped cap layer over the channel of the device, for which the III-N material is orientated in an N-polar orientation.

Abstract: A novel design for a nitrogen polar high-electron-mobility transistor (HEMT) structure comprising a GaN/InGaN composite channel. As A novel design for a nitrogen polar high-electron-mobility transistor (HEMT) structure comprising a GaN/InGaN composite channel. As illustrated herein, a thin InGaN layer introduced in the channel increases the carrier density, reduces the electric field in the channel, and increases the carrier mobility. The dependence of p on InGaN thickness (tInGaN) and indium composition (xIn) was investigated for different channel thicknesses. With optimized tInGaN and xIn, significant improvements in electron mobility were observed. For a 6 nm channel HEMT, the electron mobility increased from 606 to 1141 cm2/(V·s) when the 6 nm thick pure GaN channel was replaced by the 4 nm GaN/2 nm In0.1Ga0.9N composite channel.

Abstract: An optoelectronic or electronic device structure, including an active region on or above a polar substrate, wherein the active region comprises a polar p region. The device structure further includes a hole supply region on or above the active region. Holes in the hole supply region are driven by a field into the active region, the field arising at least in part due to a piezoelectric and/or spontaneous polarization field generated by a composition and grading of the active region.

Abstract: Trenched vertical power field-effect transistors with improved on-resistance and/or breakdown voltage are fabricated. In one or more embodiments, the modulation of the current flow of the transistor occurs in the lateral channel, whereas the voltage is predominantly held in the vertical direction in the off-state. When the device is in the on-state, the current is channeled through an aperture in a current-blocking region after it flows under a gate region into the drift region. In another embodiment, a novel vertical power low-loss semiconductor multi-junction device in III-nitride and non-III-nitride material system is provided. One or more multi-junction device embodiments aim at providing enhancement mode (normally-off) operation alongside ultra-low on resistance and high breakdown voltage.

Abstract: A transistor includes a III-N layer structure including a III-N channel layer between a III-N barrier layer and a III-N depleting layer, where the III-N channel layer includes a 2DEG channel formed adjacent an interface between the III-N channel layer and the III-N barrier layer; a source and a drain, each of which being directly connected to the III-N channel layer; a gate between the source and the drain, the gate being over the III-N layer structure, where the III-N depleting layer includes a first portion that is disposed in a device access region between the gate and the drain; and where the source electrically contacts the first portion of the III-N depleting layer, and the drain is electrically isolated from the first portion of the III-N depleting layer.

Abstract: A transistor includes a III-N layer structure including a III-N channel layer between a III-N barrier layer and a III-N depleting layer, where the III-N channel layer includes a 2DEG channel formed adjacent an interface between the III-N channel layer and the III-N barrier layer; a source and a drain, each of which being directly connected to the III-N channel layer; a gate between the source and the drain, the gate being over the III-N layer structure, where the III-N depleting layer includes a first portion that is disposed in a device access region between the gate and the drain; and where the source electrically contacts the first portion of the III-N depleting layer, and the drain is electrically isolated from the first portion of the III-N depleting layer.

Abstract: A method of fabricating a semiconductor device can include forming a III-N semiconductor layer in a reactor and injecting a hydrocarbon precursor into the reactor, thereby carbon doping the III-N semiconductor layer and causing the III-N semiconductor layer to be insulating or semi-insulating. A semiconductor device can include a substrate and a carbon doped insulating or semi-insulating III-N semiconductor layer on the substrate. The carbon doping density in the III-N semiconductor layer is greater than 5×1018 cm?3 and the dislocation density in the III-N semiconductor layer is less than 2×109 cm?2.

Abstract: A transistor includes a III-N layer structure comprising a III-N channel layer between a III-N barrier layer and a p-type III-N layer. The transistor further includes a source, a drain, and a gate between the source and the drain, the gate being over the III-N layer structure. The p-type III-N layer includes a first portion that is at least partially in a device access region between the gate and the drain, and the first portion of the p-type III-N layer is electrically connected to the source and electrically isolated from the drain. When the transistor is biased in the off state, the p-type layer can cause channel charge in the device access region to deplete as the drain voltage increases, thereby leading to higher breakdown voltages.

Abstract: Embodiments of the present disclosure include a buffer structure suited for III-N device having a foreign substrate. The buffer structure can include a first buffer layer having a first aluminum composition and a second buffer layer formed on the first buffer layer, the second buffer layer having a second aluminum composition. The buffer structure further includes a third buffer layer formed on the second buffer layer at a second interface, the third buffer layer having a third aluminum composition. The first aluminum composition decreases in the first buffer layer towards the interface and the second aluminum composition throughout the second buffer layer is greater than the first aluminum composition at the interface.

Abstract: Trenched vertical power field-effect transistors with improved on-resistance and/or breakdown voltage are fabricated. In one or more embodiments, the modulation of the current flow of the transistor occurs in the lateral channel, whereas the voltage is predominantly held in the vertical direction in the off-state. When the device is in the on-state, the current is channeled through an aperture in a current-blocking region after it flows under a gate region into the drift region. In another embodiment, a novel vertical power low-loss semiconductor multi-junction device in III-nitride and non-III-nitride material system is provided. One or more multi-junction device embodiments aim at providing enhancement mode (normally-off) operation alongside ultra-low on resistance and high breakdown voltage.

Abstract: A transistor includes a III-N layer structure comprising a III-N channel layer between a III-N barrier layer and a p-type III-N layer. The transistor further includes a source, a drain, and a gate between the source and the drain, the gate being over the III-N layer structure. The p-type III-N layer includes a first portion that is at least partially in a device access region between the gate and the drain, and the first portion of the p-type III-N layer is electrically connected to the source and electrically isolated from the drain. When the transistor is biased in the off state, the p-type layer can cause channel charge in the device access region to deplete as the drain voltage increases, thereby leading to higher breakdown voltages.

Abstract: A transistor includes a III-N layer structure comprising a III-N channel layer between a III-N barrier layer and a p-type III-N layer. The transistor further includes a source, a drain, and a gate between the source and the drain, the gate being over the III-N layer structure. The p-type III-N layer includes a first portion that is at least partially in a device access region between the gate and the drain, and the first portion of the p-type III-N layer is electrically connected to the source and electrically isolated from the drain. When the transistor is biased in the off state, the p-type layer can cause channel charge in the device access region to deplete as the drain voltage increases, thereby leading to higher breakdown voltages.