Thick nitride semiconductor structures with interlayer structures and methods of fabricating thick nitride semiconductor structures
A semiconductor structure includes a substrate, a nucleation layer on the substrate, a compositionally graded layer on the nucleation layer, and a layer of a nitride semiconductor material on the compositionally graded layer. The layer of nitride semiconductor material includes a plurality of substantially relaxed nitride interlayers spaced apart within the layer of nitride semiconductor material. The substantially relaxed nitride interlayers include aluminum and gallium and are conductively doped with an n-type dopant, and the layer of nitride semiconductor material including the plurality of nitride interlayers has a total thickness of at least about 2.0 μm.
1. A method of forming a semiconductor structure, comprising:
heating a silicon substrate in a reactor chamber including H 2 and a silicon-containing gas to thereby at least one of reduce a formation of SiN and remove SiO 2 , and
thereafter forming a nucleation layer on the substrate, wherein providing a silicon-containing gas in the reactor chamber comprises flowing an amount of silicon-containing gas across the silicon substrate to achieve a vapor pressure equal to an equilibrium vapor pressure over silicon at a desorption temperature.
2. The method of claim 1 , further comprising cleaning the substrate with at least one of hydrofluoric acid and a buffered oxide etch solution before flowing the silicon containing gas across the substrate.
3. The method of claim 1 , wherein forming the nucleation layer comprises forming the nucleation layer at a temperature of 1000° C. to 1100° C.
4. The method of claim 1 , wherein the silicon-containing gas comprises at least one of SiH 4 , Si 2 H 6 , SiCl 4 , SiBr 4 , and Si 3 N 4 .
5. The method of claim 1 , wherein providing the silicon-containing gas comprises flowing the silicon-containing gas across the substrate at a temperature of 1000° C. and a pressure of 0.2 atmospheres.
6. The method of claim 1 , wherein the nucleation layer comprises AIN.
7. The method of claim 1 , wherein a ratio of the silicon-containing gas to H 2 is 10 −7 :1.
8. The method of claim 1 , wherein providing the silicon-containing gas comprises providing a silicon coating on one or more parts of the reactor, or placing solid silicon upstream from the substrate in the reactor.
9. The method of claim 1 , wherein forming the nucleation layer comprises flowing an aluminum-containing gas before flowing a nitrogen-containing gas.
10. The method of claim 1 , wherein heating a silicon substrate in a reactor chamber including H 2 and a silicon-containing gas to thereby at least one of reduce a formation of SiN and/or remove SiO 2 comprises supplying the silicon-containing gas with a hydrogen carrier gas.