Termination and Contact Structures for a High Voltage Gan-Based Heterojunction Transistor

Abstract

A semiconductor device is provided that includes a substrate, a first active layer disposed over the substrate, and a second active layer disposed on the first active layer. The second active layer has a higher bandgap than the first active layer such that a two-dimensional electron gas layer arises between the first active layer and the second active layer. A termination layer, which is disposed on the second active layer, includes InGaN. Source, gate and drain contacts are disposed on the termination layer.

1 - 20 . (canceled) 
     
     
         21 . A method of fabricating high electron mobility transistor (HEMT) comprising:
 depositing a nucleation layer on a substrate;   forming a first active layer over the nucleation layer;   forming a second active layer over the first active layer, the second active layer having a higher bandgap than the first active layer such that a two-dimensional conduction channel is formed in an interface region between the first active layer and the second active layer;   forming a flash layer over the second active layer that passivates a surface of the HEMT;   forming a gate contact disposed on the flash layer; and   forming a source contact and a drain contact respectively disposed in first and second recesses that extend through the flash layer into the second active layer.   
     
     
         22 . The method according to  claim 21 , wherein the first active layer comprises a group Ill nitride semiconductor material. 
     
     
         23 . The method according  claim 21 , wherein the first active layer comprises GaN. 
     
     
         24 . The method according to  claim 21 , wherein the second active layer comprises a group III nitride semiconductor material. 
     
     
         25 . The method according to  claim 24 , wherein the second active layer comprises Al X Ga 1-X N, wherein 0<X<1. 
     
     
         26 . The method according to  claim 21 , wherein the forming of the flash layer is performed in situ in a reactive chamber absent of a nitrogen-containing gas. 
     
     
         27 . The method according to  claim 26 , wherein the flash layer comprises Al without a nitrogen component. 
     
     
         28 . The method according to  claim 21  wherein the flash layer comprises Ga. 
     
     
         29 . The method according to  claim 21  wherein the flash layer comprises In. 
     
     
         30 . The method according to  claim 21  further comprising annealing the flash layer. 
     
     
         31 . The method according to  claim 21  further comprising oxidizing the flash layer.