The influence of iodine on the electrical properties of lead phthalocyanine (PbPC) interdigital planar gas sensors

Abstract

The electrical behaviour of AuPbPcAu planar gas sensors is studied as a function of exposure to I2–air mixture. The changes in the I–U characteristics of PbPc thin films on exposure to iodine and after subsequent annealing in vacuum at various temperatures are investigated. It is found that iodine generates acceptor levels within the PbPc energy band gap. The dark current in the devices is studied as a function of temperature and film thickness at a constant bias voltage. The effects of iodine exposure on the film surface and bulk conductivity are identified. The response time and operating conditions for PbPc thin film iodine gas sensors are also reported.

Optical and structural properties of CuO nanofilm: Its diode application

“…The exponent m depends on the nature of the transition, m = 1/2, 2, 3/2, or 3 for allowed direct, allowed non-direct, forbidden direct or forbidden non-direct transitions, respectively. The absorption (˛≥ 10 4 cm −1 ) is related to direct band transitions [31][32][33]. Fig.…”

Optical Properties of Evaporated Iron Phthalocyanine(FePc) Thin Films

“…The absorption ((1 ~ 10 4 em -I) is related to direct band transitions [16]. The variation in absorption coefficient with photon energy for direct band-lo-band transitions is of the form (5) where E s the energy gap.…”

“…showing the existence of a direct allowed gap which was found to be 2.63±O.02 e V for films before and after annealing. These values of the energy gap result in the intense band called the Sorel band and can be interpreted as a maximum in refractive index because the absorption index at that photon energy is quite small [16). The energy gap can also be estimated from the onset of the absorption spectrum [16] Fig.…”

“…These values of the energy gap result in the intense band called the Sorel band and can be interpreted as a maximum in refractive index because the absorption index at that photon energy is quite small [16). The energy gap can also be estimated from the onset of the absorption spectrum [16] Fig. 7 which has a value of 1.38±O.02 e V foe films before and after annealing.…”

Influence of γ-irradiation on optical properties of manganese phthalocyanine thin films

“…The dependence of (˛h ) r on photon energy (h ) for onset gaps was plotted for different values of r, the best fit was obtained for r = 1/2 . This characteristic behaviour of indirect allowed transitions in solid materials, is similar to NiPc [20] and CoPc [21] and unlike with others metal phthalocyanines, where the transition is a direct allowed [24,25], according to the relation:…”