1. An n-type semiconductor device comprising:
a substrate;
a source electrode, a drain electrode, and a gate electrode;
a semiconductor layer in contact with the source electrode and the drain electrode;
a gate insulating layer insulating the semiconductor layer from the gate electrode; and
a second insulating layer in contact with the semiconductor layer on the . opposite side of the semiconductor layer from the gate insulating layer;
wherein the semiconductor layer contains a carbon nanotube composite having a conjugated polymer attached to at least a part of the surface thereof; and
wherein the second insulating layer contains an organic compound containing a bond between a carbon atom and a nitrogen atom.
2. The n-type semiconductor device according to claim 1, wherein the conjugated polymer comprises, in the repeating units thereof, a fused heteroaryl unit having a nitrogen-containing double bond in the ring thereof and a thiophene unit. •' '
3. The n-type semiconductor device according to claim 1 or 2, wherein the second insulating layer comprises one or more compounds selected from the following general formulae (1) and (2):

(wherein R1 to R4 independently represent a group constituted by one or more atoms selected from a hydrogen atom(s), a carbon atom(s), a nitrogen atom(s), an oxygen atom(s), a silicon atom(s), a phosphorus atom(s), and a sulfur atom(s); and
X1 and X2 independently represent a group represented by the following general
(wherein R5 to R13 independently represent a group constituted by one or more atoms selected from a hydrogen atom(s), a carbon atom(s), a nitrogen atom(s), an oxygen atom(s), a silicon atom(s), a phosphorus atom(s), and a sulfur atom(s)).
4. The n-type semiconductor device according to claim 3, wherein R1 to R13 in the general formulae (1) to (8) are hydrocarbon groups.
5. The n-type semiconductor device according to any one of claims 1 to 4, wherein the second insulating layer comprises an amine compound having a ring structure.

6. The n-type semiconductor device according to any one of claims 3 to 5, wherein the second insulating layer comprises an organic compound having a structure of the general formula (1) or (2) and containing a ring structure containing the nitrogen atom shown in the formula (1) or (2) as a heteroatom.
7. The n-type semiconductor device according to any one of claims 3 to 6, wherein the second insulating layer comprises one or more compounds selected .from an amidine compound and a guanidine compound.
8. The n-type semiconductor device according to any one of claims 1 to 7, wherein the gate insulating layer comprises an organic compound containing a bond between a silicon atom and a carbon atom. *
9. The n-type semiconductor device according to any one of claims 1 to 8, wherein the gate insulating layer further comprises a metal compound containing a bond between a metal atom and an oxygen atom.
10. The n-type semiconductor device according to claim 9, wherein the metal atom
i
is aluminum. ""
11. An n-type semiconductor device comprising:
a substrate;
a source electrode, a drain electrode, and a gate electrode;
a semiconductor layer in contact with the source electrode and the drain
electrode; • :.
a gate insulating layer insulating the semiconductor layer from the gate
electrode; and - "

a second insulating layer in contact with the semiconductor layer on the opposite side of the semiconductor layer from the gate insulating layer; wherein the semiconductor layer contains a carbon nanotube; and wherein the second insulating layer contains an organic compound having a
(wherein R4 represents a group constituted by one or more atoms selected from a hydrogen atom(s), a carbon atom(s), a nitrogen atom(s), an oxygen atom(s), a silicon atom(s), a phosphorus atom(s), and a sulfur atom(s); and
X1 and X2 independently represent a group represented by the following general

from a hydrogen atom(s), a carbon atom(s), a nitrogen atom(s), an oxygen atom(s), a silicon atom(s), a phosphorus atom(s), and a sulfur atom(s)).
12. The n-type semiconductor device according to claim 11, wherein the second insulating layer comprises an organic compound having a structure of the general formula (2) and containing a ring structure containing the nitrogen atom shown in the general formula (2) as a heteroatom.
13. The n-type semiconductor device according to any one of claims 1 or 12, wherein the total length of the carbon nanotube composite present per 1 um2 of the semiconductor layer is 1 um to 50 urn. • ...
14. A complementary semiconductor device comprising the n-type semiconductor device according to any one of claims 1 to 13 and ap-type semiconductor device,
wherein the p-type semiconductor device comprises:
a substrate; a source electrode, a drain electrode, and a gate electrode; *
a semiconductor layer in contact with the source electrode and the drain electrode; and
a gate insulating layer insulating the semiconductor layer from the gate insulating layer;
wherein the semiconductor layer of the p-type semiconductor device contains a carbon nanotube composite having a conjugated polymer attached to at least a part of the surface thereof.
15. The complementary semiconductor device according to claim 14, wherein the p-
type semiconductor device comprises a second insulating layer in contact with the

semiconductor layer of the p-type semiconductor device on the opposite side of the semiconductor layer of the p-type semiconductor device from the gate insulating layer of the p-type semiconductor device.
16. The complementary semiconductor device according to claim 14 or 15, wherein the source electrode and the drain electrode of the p-type semiconductor device and . the source electrode and the drain electrode of the n-type semiconductor device are all composed of the same material.
17. The complementary semiconductor device according to any one of claims 14 to
16, wherein the semiconductor layer of the p-type semiconductor device and the
semiconductor layer of the n-type semiconductor device are composed of the same
material.
18. The complementary semiconductor device according to any one of claims 14 to
17, wherein the gate insulating layer of the p-type semiconductor device and the gate
insulating layer of the n-type semiconductor device are composed of the same
material.
19. A method of producing the n-type semiconductor device according to any one of claims 1 to 13, the method comprising the step of forming the semiconductor layer of the n-type semiconductor device by applying and drying the layer.
20. A method of producing the n-type semiconductor device according to any one of claims 1 to 13, the method comprising the step of forming the second insulating layer by applying a composition containing an organic compound containing a bond between a carbon atom and a nitrogen atom and drying the composition.

21. A method of producing the complementary semiconductor device according to
any one of claims 14 to 18, the method comprising the steps of:
(1) forming the source electrode and the drain electrode of the p-type semiconductor device and the source electrode and the drain electrode of the n-type semiconductor device in the same step;
(2) forming the gate insulating layer of the p-type semiconductor device and the gate insulating layer of the n-type semiconductor device in the same step; and
(3) forming the semiconductor layer of the p-type semiconductor device and the semiconductor layer of the n-type semiconductor device in the same step.

22. A wireless communication device comprising at least the n-type semiconductor device according to any one of claims 1 to 13 and an antenna.
23. A wireless communication device comprising at least the complementary semiconductor device according to any one of claims 14 to 18 and an antenna.