CARBON DOPING SEMICONDUCTOR DEVICES
A method of fabricating a semiconductor device can include forming a III-N semiconductor layer in a reactor and injecting a hydrocarbon precursor into the reactor, thereby carbon doping the III-N semiconductor layer and causing the III-N semiconductor layer to be insulating or semi-insulating. A semiconductor device can include a substrate and a carbon doped insulating or semi-insulating III-N semiconductor layer on the substrate. The carbon doping density in the III-N semiconductor layer is greater than 5×10 18 cm −3 and the dislocation density in the III-N semiconductor layer is less than 2×10 9 cm −2 .
1 . A method of fabricating a semiconductor material structure, the method comprising:
forming a III-N semiconductor layer on a substrate in a reactor, the forming of the III-N semiconductor layer comprising simultaneously injecting into the reactor a first precursor, a second precursor different from the first precursor, and a group-V precursor, wherein the first precursor is a group-III precursor and the second precursor is a hydrocarbon precursor, and the injecting of the hydrocarbon precursor causes the III-N semiconductor layer to be carbon doped.
2 . The method of claim 1 , wherein the hydrocarbon precursor comprises molecules having a chemical formula (C x H y ), where x and y are integers greater than or equal to 1, and the group-III precursor comprises a metalorganic precursor.
3 . The method of claim 1 , wherein forming the III-N semiconductor layer on the substrate comprises forming the III-N semiconductor layer as a III-N buffer layer over a III-N nucleation layer over a silicon substrate.
4 . The method of claim 3 , further comprising forming a III-N channel layer over the III-N buffer layer and forming a III-N barrier layer over the III-N channel layer, thereby forming a two-dimensional electron gas (2DEG) active channel adjacent to an interface between the channel layer and the barrier layer.
5 . The method of claim 4 , wherein the barrier layer comprises AlGaN, the channel layer comprises undoped or unintentionally doped (UID) GaN, and the buffer layer comprises AlGaN or GaN or both.
6 . The method of claim 1 , wherein the hydrocarbon precursor comprises propane or methane or both.
7 . The method of claim 1 , wherein causing the III-N semiconductor layer to be carbon doped results in the III-N semiconductor layer having a carbon concentration greater than ×10 18 cm 3 .
8 . The method of claim 1 , wherein forming the III-N semiconductor layer on the substrate comprises forming the III-N semiconductor layer by metal organic chemical vapor deposition (MOCVD).
9 . A method of fabricating a semiconductor material structure, the method comprising:
forming a III-N semiconductor layer on a substrate in a reactor, the forming of the III-N semiconductor layer comprising simultaneously injecting into the reactor a group-III precursor selected from the group consisting of TMGa and TMAl, a group-V precursor, and a hydrocarbon precursor comprising molecules having a chemical formula (C x H y ), where x and y are integers greater than or equal to 1; wherein the injecting of the hydrocarbon precursor causes the III-N semiconductor layer to be carbon doped.
10 . The method of claim 9 , wherein the injecting of the group-III precursor into the reactor comprises injecting the group-III precursor at a group-III precursor molar flow rate, and the injecting of the hydrocarbon precursor into the reactor comprises injecting the hydrocarbon precursor at a hydrocarbon precursor molar flow rate different from the group-III precursor molar flow rate.
11 . The method of claim 10 , wherein the hydrocarbon precursor molar flow rate is at least 0.02 times the group-III precursor molar flow rate.
12 . The method of claim 11 , wherein the hydrocarbon precursor molar flow rate is greater than the group-III precursor molar flow rate.
13 . The method of claim 9 , wherein the hydrocarbon precursor comprises propane or methane or both.
14 . The method of claim 9 , wherein forming the III-N semiconductor layer on the substrate comprises forming the III-N semiconductor layer by metal organic chemical vapor deposition (MOCVD).
15 . A method of fabricating a semiconductor material structure, the method comprising:
forming a first III-N semiconductor layer in a reactor, the first III-N semiconductor layer being carbon doped; and
forming a second III-N semiconductor layer on the first III-N semiconductor layer in the reactor; wherein
the forming of the first III-N semiconductor layer comprises injecting into the reactor a group-III precursor, a group-V precursor, and a hydrocarbon precursor, and the forming of the second III-N semiconductor layer comprises injecting into the reactor the group-III precursor and the group-V precursor but not the hydrocarbon precursor.
16 . The method of claim 15 , wherein the second III-N semiconductor layer is undoped or unintentionally doped.
17 . The method of claim 15 , wherein the group-III precursor comprises TMGa or TMAl, the group-V precursor comprises ammonia, and the hydrocarbon precursor comprises molecules having a chemical formula (C x H y ), where x and y are integers greater than or equal to 1.
18 . The method of claim 15 , wherein the carbon concentration in the first III-N semiconductor layer is in excess of 1×10 17 cm −3 .
19 . The method of claim 15 , wherein the hydrocarbon precursor comprises propane or methane or both.
20 . The method of claim 15 , wherein forming the III-N semiconductor layer on the substrate comprises forming the III-N semiconductor layer by metal organic chemical vapor deposition (MOCVD).