Power semiconductor devices incorporating single crystalline aluminum nitride substrate

Abstract

The invention provides a power semiconductor device including an aluminum nitride single crystalline substrate, wherein the dislocation density of the substrate is less than about 10 5 cm −2 and the Full Width Half Maximum (FWHM) of the double axis rocking curve for the (002) and (102) crystallographic planes is less than about 200 arcsec; and a power semiconductor structure comprising at least one doped Al x Ga 1-x N layer overlying the aluminum nitride single crystalline substrate.

What is claimed is: 
     
         1 . A power semiconductor device, comprising:
 an aluminum nitride single crystalline substrate, wherein the dislocation density of the substrate is less than about 10 5  cm −2  and the Full Width Half Maximum (FWHM) of the double axis rocking curve for the (002) and (102) crystallographic planes is less than about 200 arcsec; and   a power semiconductor structure comprising a plurality of epitaxial doped Al x Ga 1-x N layers overlying the aluminum nitride single crystalline substrate.   
     
     
         2 . The power semiconductor device of  claim 1 , wherein the dislocation density of the substrate is lower than 10 4  cm −2 . 
     
     
         3 . The power semiconductor device of  claim 1 , wherein the dislocation density of the substrate is lower than 10 3  cm −2 . 
     
     
         4 . The power semiconductor device of  claim 1 , wherein the dislocation density of the substrate is lower than 10 2  cm −2 . 
     
     
         5 . The power semiconductor device of  claim 1 , wherein the FWHM of the double axis rocking curve for the (002) and (102) crystallographic planes is less than about 100 arcsec. 
     
     
         6 . The power semiconductor device of  claim 1 , wherein the FWHM of the double axis rocking curve for the (002) and (102) crystallographic planes is less than about 50 arcsec. 
     
     
         7 . The power semiconductor device of  claim 1 , wherein the FWHM of the double axis rocking curve for the (002) and (102) crystallographic planes is less than about 25 arcsec. 
     
     
         8 . The power semiconductor device of  claim 1 , wherein the power semiconductor structure is in the form of a Schottky diode, a Junction Field Effect Transistors (JFET), or a Power Metal Oxide Semiconductor Field Effect Transistors (MOSFET). 
     
     
         9 . The power semiconductor device of  claim 1 , wherein the power semiconductor structure is in the form of a Schottky diode comprising a relatively lightly doped N-type drift region comprising one or more epitaxial Al x Ga 1-x N layers adjacent to a relatively heavily doped N+ region comprising one or more epitaxial Al x Ga 1-x N layers. 
     
     
         10 . The power semiconductor device of  claim 9 , wherein at least one layer of doped Al x Ga 1-x  N has a value for x greater than about 0.7. 
     
     
         11 . The power semiconductor device of  claim 1 , wherein the aluminum nitride single crystalline substrate is prepared by physical vapor transport. 
     
     
         12 . The power semiconductor device of  claim 1 , wherein the device is characterized by one or more of the following:
 a breakdown field of at least about 5 MV/cm;   a blocking voltage of at least about 20 kV; and   a switching frequency of at least about 20 kHz.   
     
     
         13 . A method of forming a power semiconductor device, comprising:
 receiving an aluminum nitride single crystalline substrate, wherein the dislocation density of the substrate is less than about 10 5  cm −2  and the Full Width Half Maximum (FWHM) of the double axis rocking curve for the (002) and (102) crystallographic planes is less than about 200 arcsec;   depositing a plurality of epitaxial doped Al x Ga 1-x N active layers on the aluminum nitride single crystalline substrate; and   forming metal electrode layers in contact with the doped Al x Ga 1-x N active layers.   
     
     
         14 . The method of  claim 13 , wherein the depositing step comprises molecular-beam epitaxy (MBE), metal organic chemical vapor deposition (MOCVD), or Hydride Vapor Phase Epitaxy (HVPE). 
     
     
         15 . The method of  claim 13 , wherein the power semiconductor structure is in the form of a Schottky diode and the depositing step comprises depositing one or more relatively heavily doped N+ Al x Ga 1-x N layers on the aluminum nitride single crystalline substrate and depositing one or more relatively lightly doped N-type Al x Ga 1-x N layers on the relatively heavily doped N+Al x Ga 1-x N layers.