Creation and investigation of electronic defects on methylammonium lead iodide (CH$$_3$$NH$$_3$$PbI$$_3$$) films depending on atmospheric conditions

Methylammonium lead iodide (MAPbI$$_3$$ 3 ) (CH$$_3$$ 3 NH$$_3$$ 3 PbI$$_3$$ 3 ) is popular material for edge technology application, but it still includes many uncertainties. Particularly, molecular and electronic degradation (electronic defect distribution) and mobility–lifetime product still hold many mysteries. Stemming from the atmospheric or light-induced degradation, mobility–lifetime product changes are still unknown and haven’t been studied up to now. In this study, mobility–lifetime product change was investigated depending on degradation source such as atmospheric and light soaked. MAPbI$$_3$$ 3 films were deposited by thermal chemical vapor deposition (thermal CVD). Structural analysis was done by X-ray diffraction (XRD), respectively. Deposited MAPbI$$_3$$ 3 films were exposed to laboratory ambient, vacuum atmosphere, deionized water vapor (DIWV) atmosphere and UV light soaking at constant temperature (300K) to define changes on mobility–lifetime product.

Summary of New Insight into Electron Transport in Metals

This paper gives a summary of a new insight into basic electron transport characteristics in crystalline elemental metals. The general expressions based on the Fermi-Dirac distribution of the effective density of the randomly moving electrons, their diffusion coefficient, drift mobility, and other characteristics, including the Einstein relation between diffusion coefficient and drift mobility, are presented. It is shown that the creation of the randomly moving electrons due to lattice atom vibrations produces the same number of electronic defects, which cause scattering of the randomly moving electrons and related transport characteristics.

Surface passivation of germanium by atomic layer deposited Al2O3 nanolayers

Surfaces of semiconductors are notorious for the presence of electronic defects such that passivation approaches are required for optimal performance of (opto)electronic devices. For Ge, thin films of Al2O3 prepared by atomic layer deposition (ALD) can induce surface passivation; however, no extensive study on the effect of the Al2O3 process parameters has been reported. In this work we have investigated the influence of the Al2O3 thickness (1–44 nm), substrate temperature (50–350 °C), and post-deposition anneal (in N2, up to 600 °C). We demonstrated that an effective surface recombination velocity as low as 170 cm s−1 can be achieved. The role of the GeOx interlayer as well as the presence of interface charges was addressed and a fixed charge density $${Q}_{\mathrm{f}}=$$ Q f = −(1.8 ± 0.5) × 1012 cm−2 has been found. The similarities and differences between the passivation of Ge and Si surfaces by ALD Al2O3 prepared under the same conditions are discussed. Graphic Abstract