Crystal growth method for nitride semiconductor having a multiquantum well structure

Abstract

A crystal growth method for nitride semiconductors, including the steps of growing a first semiconductor layer containing In x Ga 1-x N (0<x≦1) on a substrate, with the use of a first carrier gas formed with an inert gas; growing a second semiconductor layer containing In y Ga 1-y N (0≦y<1, y<x) on the first semiconductor layer, with the use of a second carrier gas containing the inert gas and H 2 gas, an amount of the H 2 gas being smaller than an amount of the inert gas; and growing a third semiconductor layer containing In z Ga 1-z N (0≦z<1, z<x) on the second semiconductor layer, with the use of a third carrier gas containing the inert gas and H 2 gas, an amount of the H 2 gas in the third carrier gas being a smaller than the amount of H 2 gas in the second carrier gas.

1 . (canceled) 
     
     
         2 . A crystal growth method for nitride semiconductors, comprising:
 growing a first semiconductor layer containing In x Ga 1-x N (0<x≦1) on a substrate, with the use of a first carrier gas formed with an inert gas;   growing a second semiconductor layer containing In y Ga 1-y N (0≦y<1, y<x) on the first semiconductor layer, with the use of a second carrier gas containing the inert gas and H 2  gas, an amount of the H 2  gas being smaller than an amount of the inert gas; and   growing a third semiconductor layer containing In z Ga 1-z N (0≦z<1, z<x) on the second semiconductor layer, with the use of a third carrier gas containing the inert gas and H 2  gas, an amount of the H 2  gas in the third carrier gas being a smaller than the amount of H 2  gas in the second carrier gas.   
     
     
         3 . The method according to  claim 2 , wherein the third semiconductor layer has substantially the same composition as the second semiconductor layer. 
     
     
         4 . The method according to  claim 2 , wherein
 procedures for growing the first semiconductor layer, the second semiconductor layer, and the third semiconductor layer are set as one cycle, and   a plurality of cycles each being the one cycle are repeated.   
     
     
         5 . The method according to  claim 2 , further comprising
 growing a fourth semiconductor layer containing In u Ga 1-u N (0≦u<1, u<x) with the use of the first carrier gas before the first semiconductor layer is grown.   
     
     
         6 . The method according to  claim 2 , further comprising
 growing a fifth semiconductor layer containing In v Ga 1-v N (0≦v<1, v<x) with the use of the first carrier gas after the first semiconductor layer is grown but before the second semiconductor layer is grown.   
     
     
         7 . The method according to  claim 2 , wherein the second and third semiconductor layers are GaN layers. 
     
     
         8 . The method according to  claim 2 , wherein the first semiconductor layer is grown at a first growth temperature of 700° C. or higher but not higher than 850° C., the second semiconductor layer is grown at a second growth temperature higher than the first growth temperature, and the third semiconductor layer is grown at a third growth temperature higher than the first growth temperature but not higher than the second growth temperature. 
     
     
         9 . The method according to  claim 8 , wherein the third growth temperature is higher than the first growth temperature by 50° C. or more. 
     
     
         10 . The method according to  claim 8 , wherein the third growth temperature is 800° C. or higher but not higher than the 950° C.