Investigation of deep levels in PbI2 by photoinduced current transient spectroscopy

Abstract

Deep levels in PbI2 have been investigated by photoinduced current transient spectroscopy for the first time. By separating the signal processing from the data acquisition it was possible to analyze the transient using different methods, in particular a four-gate treatment which allows to clear the detrapping current of uncontrolled changes of the recombination lifetime of thermally released carriers. Three hole traps located at 0.30, 0.47, and 0.66 eV have been detected and the corresponding thermal capture cross sections evaluated. In addition a photomemory effect has been evidenced. The main features of the excited state of the crystal are increased photosensitivity, neutralization of hole traps, and residual conductivity. It is believed that macroscopic recombination barriers acting as minority carrier traps under optical excitation are responsible for this phenomenon. The presence of these extended defects is probably related to the layered structure of PbI2. An energy model is proposed on the basis of which the observed logarithmic time dependence of the photosensitization at room temperature can be predicted. The model allows also to give a plausible interpretation for all the characteristic features of the photomemory effect and for various results previously reported by other authors.

Layered ultrathin PbI2 single crystals for high sensitivity flexible photodetectors

“…Thus, it can be speculated that PbI 2 tends to be a weak p-type or intrinsic semiconductor, which is consistent with the previous results. 25 Fig. 3 presents the low-temperature PL spectrum and the room-temperature (RT) UV-vis absorbance spectrum (the inset).…”

Identification of deep defects in high-resistivity undoped LEC-GaAs irradiated with protons

“…While traditional deep level transient spectroscopy (DLTS) based on junction capacitance has proved to be a very successful technique for studying deep levels in semiconductors [4,5], it is not useful in the study of deep levels in high-resistivity materials. Photo-induced transient spectroscopy (PICTS) is regarded as a powerful tool for the investigation of deep traps in both bulk substrates and high-resistivity epitaxial layers [6][7][8]. This technique, compared to the standard DLTS, presents some limitations such as the determination of the concentration of traps and their nature.…”

Properties of solution grown PbI2 layers embedded in PVA

“…Lead iodide is a semiconductor which presents very interesting photoconductive properties [1]. In addition to optical applications, PbI 2 single crystals can be used for room temperature X or γ-ray detection thanks to the wide band gap and high atomic number of the material.…”