Photocurrent Measurements of Carbon Nanotube Networks with Physical Adsorption of Oxygen Molecules

Abstract

We report persistent photocurrent measurements of carbon nanotube networks with various pressures of hydrogen, ammonia and oxygen gases. The maximum build-up photocurrent drops substantially as the gas pressure is increased. However, the decay time is very sensitive to the gas species. While the decay time increases significantly under oxygen, only a modest increase is observed under H(2) and NH(3). The ab initio electronic structure calculations show that a physical adsorption of O(2) molecules induces a shallow trap level within the band gap of the carbon nanotube, which is associated with an increase in the decay time.