Photoconductive Characteristics of Hydro-Oxygenated Amorphous Titanium Oxide Films Prepared by Remote Plasma-Enhanced Chemical Vapor Deposition

Abstract

The photoconductive characteristics of amorphous titanium oxide films (a-TiOx:OH) prepared by remote plasma-enhanced (RPE) chemical vapor deposition, in inert Ar atmosphere with/without a small amount of oxygen, have been studied. In inert Ar atmosphere without oxygen, the residual decay of photocurrent (long decay time) is observed after removing UV irradiation. On the other hand, in inert Ar atmosphere with a small amount of oxygen, the photocurrent under UV irradiation is influenced strongly by an environmental gas with oxygen gas. The maximum of photocurrent (photosensitivity) is nearly inversely proportional to oxygen partial pressure, suggesting that the present films are useful for sensors of environmental oxygen gases. The decay of photocurrent, after removing UV irradiation, follows a stretched exponential function. The effective decay time τ is nearly inversely proportional to oxygen partial pressure. The results will be discussed in terms of the surface reaction of oxygen gas on the present films.

Uniformity, Structure, and Photocatalytic Activity of TiO2 Films Deposited by Atmospheric‐Pressure Linear Cold Plasma

“…FTIR spectra of the TiO 2 films, as‐deposited and after calcination, were also investigated, as shown in Figure 7. The as‐deposited TiO 2 films showed a broad peak at 3379 cm −1 , assigned to the terminal OH groups which act as electron‐releasing sites,29 however the peak attributed to the terminal OH groups disappeared after calcination at 723 K. Therefore, the as‐deposited and calcined films were assigned to mainly hydro‐oxygenated amorphous (a‐TiO x :OH),29–32 and exclusively anatase structures, respectively.…”

Transport and recombination of photo‐carriers under potential fluctuation in TiOx films prepared by rf magnetron sputtering method

“…Note here that [O 2 ] is the oxygen partial pressure. As the dispersion parameter β experimentally obtained is 0.57 [12], τ is expected to be roughly inversely proportional to the oxygen partial pressure. In fact, as shown in Fig.…”

“…Figure 3 shows thep hotocurrent of titanium oxide films prepared by PECVD, in the atmosphere of Ar (3 l/min) including a small amount of oxygen (10 ml/min, 20 ml/min, 30 ml/min, 50 ml/min) [12]. Photocurrent at a constant voltage (20V) was measured at 303K.…”

“…In argon and oxygen mixed gas atmosphere, the decay current is known to be described by a stretched exponential form [11,12]. It is clear that oxygen molecules attacking on the surface play a main role for the carrier recombination.…”

Highly conductive titanium oxide films by RF magnetron sputtering

“…Usually these films are optically transparent in visible region and highly resistive [1,2]． Irradiating UV light generates photo-current as like a semiconductor material [3][4][5][6]. .…”