Electronic Properties and Structure of Boron–Hydrogen Complexes in Crystalline Silicon

From Wiley via Jisc Publications RouterHistory: received 2021-06-27, rev-recd 2021-09-04, pub-electronic 2021-09-17Article version: VoRPublication status: PublishedFunder: Department of Science and Technology (DOST), Government of the PhlippinesFunder: Fundação para a Ciência e a Tecnologia in Portugal; Grant(s): UIDB/50025/2020, UIDP/50025/2020The subject of hydrogen–boron interactions in crystalline silicon is revisited with reference to light and elevated temperature‐induced degradation (LeTID) in boron‐doped solar silicon. Ab initio modeling of structure, binding energy, and electronic properties of complexes incorporating a substitutional boron and one or two hydrogen atoms is performed. From the calculations, it is confirmed that a BH pair is electrically inert. It is found that boron can bind two H atoms. The resulting BH2 complex is a donor with a transition level estimated at E c–0.24 eV. Experimentally, the electrically active defects in n‐type Czochralski‐grown Si crystals co‐doped with phosphorus and boron, into which hydrogen is introduced by different methods, are investigated using junction capacitance techniques. In the deep‐level transient spectroscopy (DLTS) spectra of hydrogenated Si:P + B crystals subjected to heat‐treatments at 100 °C under reverse bias, an electron emission signal with an activation energy of ≈0.175 eV is detected. The trap is a donor with electronic properties close to those predicted for boron–dihydrogen. The donor character of BH2 suggests that it can be a very efficient recombination center of minority carriers in B‐doped p‐type Si crystals. A sequence of boron–hydrogen reactions, which can be related to the LeTID effect in Si:B is proposed

Indium‐Doped Silicon for Solar Cells—Light‐Induced Degradation and Deep‐Level Traps

From Wiley via Jisc Publications RouterHistory: received 2021-02-28, rev-recd 2021-06-11, pub-electronic 2021-07-21Article version: VoRPublication status: PublishedFunder: EPSRC (UK); Grant(s): EP/TO25131/1Funder: Department of Science and Technology (DOST), Government of the PhlippinesFunder: Fundação para a Ciência e a Tecnologia; Id: http://dx.doi.org/10.13039/100008382; Grant(s): UIDB/50025/2020, UIDP/50025/2020Indium‐doped silicon is considered a possible p‐type material for solar cells to avoid light‐induced degradation (LID), which occurs in cells made from boron‐doped Czochralski (Cz) silicon. Herein, the defect reactions associated with indium‐related LID are examined and a deep donor is detected, which is attributed to a negative‐U defect believed to be InsO2. In the presence of minority carriers or above bandgap light, the deep donor transforms to a shallow acceptor. An analogous transformation in boron‐doped material is related to the BsO2 defect that is a precursor of the center responsible for BO LID. The electronic properties of InsO2 are determined and compared to those of the BsO2 defect. Structures of the BsO2 and InsO2 defects in different charges states are found using first‐principles modeling. The results of the modeling can explain both the similarities and the differences between the BsO2 and InsO2 properties

Standart for the capacity of Kos amphorae IV – I centuries BC

The article describes a method for calculating the volume of amphorae using the three-dimensional editor Blender and proposes a new fairly accurate method for calculating the volume of antique amphorae on the example of transport amphorae of the Kos island IV–I century BC. The method described in the article is based on the 3-D model of amphorae as complex bodies of revolution. The creation of an effective 3-D model of a transport amphora proves the fundamental possibility of creating similar mathematical models for amphorae in other antique centers of winemaking and trade

New Method of Oil Reservoir Rock Heterogeneity Quantitative Estimation from X-ray MCT Data

This paper considers a new method for “pore scale” oil reservoir rock quantitative estimation. The method is based on core sample X-ray tomography data analysis and can be directly used to both classify rocks by heterogeneity and assess representativeness of the core material collection. The proposed heterogeneity criteria consider the heterogeneity of pore size and heterogeneity of pore arrangement in the sample void and can thus be related to the drainage effectiveness. The classification of rocks by heterogeneity at the pore scale is also proposed when choosing a reservoir engineering method and may help us to find formations that are similar at pore scale. We analyzed a set of reservoir rocks of different lithologies using the new method that considers only tomographic images and clearly distributes samples over the structure of their pore space

Analysis of Impurity-Related Radiative Transitions in Silicon Materials Using Temperature-Dependent Photoluminescence

The contradictory reports in the literature about the stability of Ga-doped silicon (Si) material for photovoltaic applications, in comparison to those doped with B, necessitate a more detailed understanding of the characteristics of this material before solid conclusions about degradation mechanisms can be made. In this work, high-resolution low-temperature photoluminescence (PL) has been used to investigate and analyze the luminescence from Ga-doped and P+Ga co-doped Czochralski-grown silicon (Cz-Si) materials. Comparison of thermally induced changes in luminescence features for these materials are compared to those occurring in B-doped and P+B co-doped Si materials. It has been found that the Ga bound exciton (BE) exhibits a triplet luminescence structure which is preserved in the co-doped material, explained by the splitting of the exciton ground state. A similar effect does not occur for the BE-related PL signal in B-doped silicon material. A low temperature (10-20 K) range was then used to investigate the temperature-induced changes in impurity related photon emission lines in the PL spectra of the studied materials. The effect of thermal energy on the PL intensity of different radiative recombination channels is elucidated. It has been argued that the presence of compensating impurities causes enhanced radiative recombination of some excitonic emissions while others behave in a similar way as in a single-doped material. The possible relationship of the observed effects on electron-hole recombination at room temperature is discussed.</p