Transphorm Inc.

Transphorm Technology, Inc.

University of California

Rakesh K Lal

Umesh Kumar Mishra

Carl Joseph Neufeld

Yifeng Wu

Primit A Parikh

Srabanti Chowdhury

Yuvaraj Dora

Nicholas A Fichtenbaum

Geetak Gupta

David Michael Rhodes

Rongming Chu

Stacia Keller

Robert Coffie

Davide Bisi

Mo Wu

Ilan Ben-Yaacov

Brian L Swenson

Toshihide Kikkawa

Likun Shen

John Kirk Gritters

Xiang Liu

A lateral III-N device has a vertical gate module with III-N material orientated in an N-polar or a group-III polar orientation. A III-N material structure has a III-N buffer layer, a III-N barrier layer, and a III-N channel layer. A compositional difference between the III-N barrier layer and the III-N channel layer causes a 2DEG channel to be induced in the III-N channel layer. A p-type III-N body layer is disposed over the III-N channel layer in a source side access region but not over a drain side access region. A n-type III-N capping layer over the p-type III-N body layer. A source electrode that contacts the n-type III-N capping layer is electrically connected to the p-type III-N body layer and is electrically isolated from the 2DEG channel when the gate electrode is biased relative to the source electrode at a voltage that is below a threshold voltage.

Lateral III-nitride devices including a vertical gate module

Described herein are lateral III-N (e.g., GaN) devices having a III-N depleting layer. A circuit includes a depletion-mode transistor with a source connected to a drain of an enhancement-mode transistor. The gate of the depletion-mode transistor and the gate of the enhancement-mode transistor are biased at zero volts, and the drain of the depletion-mode transistor is biased at positive voltage to block a current in a forward direction. Then, the bias of the gate of the enhancement-mode transistor is changed to a first voltage greater than the threshold voltage of the enhancement-mode transistor and a first current is allowed to flow through the channel in a forward direction. Then, the bias of the gate of the depletion-mode transistor is changed to a second voltage and a second current is allowed to flow through the channel in a forward direction where the second current is greater than the first current.

N-polar devices including a depleting layer with improved conductivity

A transistor includes a III-N channel layer; a III-N barrier layer on the III-N channel layer; a source contact and a drain contact, the source and drain contacts electrically coupled to the III-N channel layer; an insulator layer on the III-N barrier layer; a gate insulator partially on the insulator layer and partially on the III-N channel layer, the gate insulator including an amorphous AlSiO layer with 0.2&#x3c;x&#x3c;0.8; and a gate electrode over the gate insulator, the gate electrode being positioned between the source and drain contacts.

Enhancement mode III-nitride devices having an Al-SiO gate insulator

A III-N device includes a III-N layer structure including a III-N channel layer, a III-N barrier layer over the III-N channel layer, and a graded III-N layer over the III-N barrier layer having a first side adjacent to the III-N barrier layer and a second side opposite the first side; a first power electrode and a second power electrode; and a gate between the first and second power electrodes, the gate being over the III-N layer structure. A composition of the graded III-N layer is graded so the bandgap of the graded III-N layer adjacent to the first side is greater than the bandgap of the graded III-N layer adjacent to the second side. A region of the graded III-N layer is (i) between the gate and the second power electrode, and (ii) electrically connected to the first power electrode and electrically isolated from the second power electrode.

III-nitride devices including a graded depleting layer

A III-N enhancement-mode transistor includes a III-N structure including a conductive channel, source and drain contacts, and a gate electrode between the source and drain contacts. An insulator layer is over the III-N structure, with a recess formed through the insulator layer in a gate region of the transistor, with the gate electrode at least partially in the recess. The transistor further includes a field plate having a portion between the gate electrode and the drain contact, the field plate being electrically connected to the source contact. The gate electrode includes an extending portion that is outside the recess and extends towards the drain contact. The separation between the conductive channel and the extending portion of the gate electrode is greater than the separation between the conductive channel and the portion of the field plate that is between the gate electrode and the drain contact.

Enhancement-mode III-nitride devices

Group III-nitride devices are described that include a stack of III-nitride layers, passivation layers, and conductive contacts. The stack includes a channel layer with a 2DEG channel, a barrier layer and a spacer layer. One passivation layer directly contacts a surface of the spacer layer on a side opposite to the channel layer and is an electrical insulator. The stack of III-nitride layers and the first passivation layer form a structure with a reverse side proximate to the first passivation layer and an obverse side proximate to the barrier layer. Another passivation layer is on the obverse side of the structure. Defected nucleation and stress management layers that form a buffer layer during the formation process can be partially or entirely removed.

Methods of forming reverse side engineered III-nitride devices

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.

III-Nitride transistor including a III-N depleting layer

A method of fabricating a III-N device includes forming a III-N channel layer on a substrate, a III-N barrier layer on the channel layer, an insulator layer on the barrier layer, and a trench in a first portion of the device. Forming the trench comprises removing the insulator layer and a part of the barrier layer in the first portion of the device, such that a remaining portion of the barrier layer in the first portion of the device has a thickness away from a top surface of the channel layer, the thickness being within a predetermined thickness range, annealing the III-N device in a gas ambient including oxygen at an elevated temperature to oxidize the remaining portion of the barrier layer in the first portion of the device, and removing the oxidized remaining portion of the barrier layer in the first portion of the device.

Forming enhancement mode III-nitride devices

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.

Growing community of inventors

Isla Vista, CA, United States of America

Rakesh K Lal