See this

This may be helpful

http://d-nb.info/1024517586/34

You can fabricate by different means, but have to care full about the energy level difference between the both materials at hetero junction, because both are more or less equal energy levels form vacuum  otherwise u can not extract any charge carriers from the junction. 

You can try to fabricate fullerence C70 (n-type with band gap 1.77 eV) on SWCNTs (p-type with band gap 0-0.5 eV) or fullerene C60 (n-type with band hap 1.6 eV) on SWCNTs (p-type).

you can deposit organic n-type by spin coating on graphene-CNT