An electron-emitting device including a protective layer that is formed on a catalyst layer to protect the catalyst layer from the deleterious environmental conditions before or during a cathode process. The present invention further includes a half etching process that is adapted to partially remove portions of the protective layer from the catalyst layer to etch the catalyst layer except carbon nano-tube growing portions. Portions of the protective layer still remain on the catalyst layer to protect the catalyst layer from the deleterious conditions from next cathode formation process.