During fabrication of single-walled carbon nanotube transistor devices, a porous template with numerous parallel pores is used to hold the single-walled carbon nanotubes. The porous template or porous structure may be anodized aluminum oxide or another material. A gate region may be provided one end or both ends of the porous structure. The gate electrode may be formed and extend into the porous structure. A transistor of the invention may be especially suited for power transistor or power amplifier applications.