Epitaxial structure and fabrication method of nitride semiconductor device

A method for fabricating a nitride semiconductor device, comprising the following steps:

• (a) preparing a substrate;
• (b) forming a first intermediate layer made of Al1-x-yGaxInyN (x, y≧0, 1≧x+y≧0) having an appropriate thickness by using a MOCVD process under an appropriate temperature;
• (c) forming a second intermediate layer made of SiiNj (i, j≧0) having an appropriate thickness on said first intermediate layer by using NH3 and a material selected from the group consisting of SiH4 and Si2H6 in a MOCVD process under an appropriate temperature;
• and
• (d) forming a nitride epitaxial layer on said second intermediate layer by using a MOCVD process under an appropriate temperature.

A nitride semiconductor device, comprising:

• a substrate;
• a lower first intermediate layer made of Al1-s-tGasIntN (s, t≧0, 1≧s+t≧0) having an appropriate thickness on top of said substrate;
• a second intermediate layer made of SieNf (e, f≧0) forming a mask having a random, clustered pattern with an appropriate thickness on top of said first intermediate layer;
• an upper first intermediate layer having an appropriate thickness made of Al1-u-vGauInvN (u, v≧0, 1≧u+v≧0) growing from said lower first intermediate layer not covered by said second intermediate layer and overflowing to cover said second intermediate layer;
• and
• a nitride epitaxial layer on top of said upper first intermediate layer.

A method for fabricating a nitride semiconductor device, comprising the following steps:

• (a) preparing a substrate;
• (b) forming a lower first intermediate layer made of Al1-s-tGasIntN (s, t≧0, 1≧s+t≧0) having an appropriate thickness on a substrate by using a MOCVD process under an appropriate temperature;
• (c) forming a second intermediate layer made of SieNf (e, f≧0) having an appropriate thickness on said lower first intermediate layer by using NH3 and a material selected from the group consisting of SiH4 and Si2H6 in a MOCVD process under an appropriate temperature;
• (d) forming an upper first intermediate layer made of Al1-u-vGauInvN (u, v≧0, 1≧u+v≧0) having an appropriate thickness on said second intermediate layer by using a MOCVD process under an appropriate temperature;
• and
• (e) forming a nitride epitaxial layer on said upper first intermediate layer by using a MOCVD process under an appropriate temperature.