Semiconductor Device

Abstract

Provided is a semiconductor device comprising: a GaN crystal substrate defining a principal, (0001) Ga face and defining a matrix, being a majority, polarity-determining domain of the GaN crystal, and inversion domains, being domains in which the polarity in the GaN crystal's [0001] direction is inverted with respect to the matrix, the GaN substrate having a ratio S t /S, of collective area S t cm 2 of inversion domains to the total area S cm 2 of the GaN substrate principal face, of no more than 0.5, with the density along the (0001) Ga face of inversion domains whose surface area is 1 μm 2 or more being D cm −2 ; and an at least single-lamina semiconductor layer on the GaN substrate principal face, the semiconductor layer defining a semiconductor-device principal face; wherein the product S c ×D of the area S c of the semiconductor-device principal face and the inversion domain density D is less than 2.3.

What is claimed is: 
     
         1 . A semiconductor device, comprising:
 a GaN crystal substrate defining a principal, (0001) Ga face and defining a matrix, being a majority, polarity-determining domain of the GaN crystal, and inversion domains, being domains in which the polarity in the GaN crystal's [0001] direction is inverted with respect to the matrix, the GaN substrate having a ratio S t /S, of collective area S t  cm 2  of inversion domains to the total area S cm 2  of the GaN substrate principal face, of no more than 0.5, with the density along the (0001) Ga face of inversion domains whose surface area is 1 μm 2  or more being D cm −2 ; and   an at least single-lamina semiconductor layer on the GaN substrate principal face, the semiconductor layer defining a semiconductor-device principal face; wherein   the product S c ×D of the area S c  of the semiconductor-device principal face and the inversion domain density D is less than 2.3.   
     
     
         2 . A semiconductor device as set forth in  claim 1 , wherein the ratio S t /S is 0.2 or less, and the product S c ×D is less than 0.7. 
     
     
         3 . A semiconductor device as set forth in  claim 1 , wherein the ratio S t /S is 0.05 or less, and the product S c ×D is less than 0.1. 
     
     
         4 . A semiconductor device as set forth in  claim 1 , wherein the area of the GaN substrate principal face is 10 cm 2  or more. 
     
     
         5 . A semiconductor device as set forth in  claim 1 , wherein the GaN substrate is a product of vapor-phase deposition. 
     
     
         6 . A semiconductor device as set forth in  claim 5 , wherein the GaN substrate is a product of hydride vapor-phase epitaxy. 
     
     
         7 . A semiconductor device as set forth in  claim 1 , wherein said semiconductor layer comprises a plurality of laminae whereby a p-n junction interface is constituted between the semiconductor laminae.