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Growth and characterisation of LWIR T2SL on (100)-, (211)- and (311)-oriented GaSb substrates

Lubyshev Dmitri, Fastenau Joel M., Kattner Michael, Frey Philip, Nelson Scott A., Flick Ryan, Wu Ying, Liu Amy W. K., Szymanski Dennis E., Martinez Becky, Furlong Mark J., Dennis Richard, Bundas Jason, Sundaram Mani

Opto-Electronics Review

2023

Vol. 31, Special Issue

art. no. e144568

Ga-free InAs/InAsSb type-II superlattice structures grown on GaSb substrates have demonstrated high performance for mid-wave infrared applications. However, realisation of long wavelength infrared photodetectors based on this material system still presents challenges, especially in terms of reduced quantum efficiency. This reduction is due, in part, to the increased type-II superlattice period required to attain longer wavelengths, as thicker periods decrease the wave-function overlap for the spatially separated quantum wells. One way to improve long wavelength infrared performance is to modify the type-II superlattice designs with a shorter superlattice period for a given wavelength, thereby increasing the wave-function overlap and the resulting optical absorption. Long wavelength infrared epitaxial structures with reduced periods have been realised by shifting the lattice constant of the type-II superlattice from GaSb to AlSb. Alternatively, epitaxial growth on substrates with orientations different than the traditional (100) surface presents another way for superlattice period reduction. In this work, the authors evaluate the performance of long wavelength infrared type-II superlattice detectors grown by molecular beam epitaxy using two different approaches to reduce the superlattice period: first, a metamorphic buffer to target the AlSb lattice parameter, and second, structures lattices matched to GaSb using substrates with different orientations. The use of the metamorphic buffer enabled a ~30% reduction in the superlattice period compared to reference baseline structures, maintaining a high quantum efficiency, but with the elevated dark current related to defects generated in the metamorphic buffer. Red-shift in a cut-off wavelength obtained from growths on highindex substrates offers a potential path to improve the infrared photodetector characteristics. Focal plane arrays were fabricated on (100), (311)A- and (211)B-oriented structures to compare the performance of each approach.

Local Characterisation and Detection of Woven Fabric Texture Based on a Sparse Dictionary

Wu Ying, Wang Ren, Lou Lin, Wang Lali, Wang Jun

Fibres & Textiles in Eastern Europe

2022

Vol. 30, no. 3

33--40

To achieve enhanced accuracy of fabric representation and defect detection, an innovative approach using a sparse dictionary with small patches was used for fabric texture characterisation. The effectiveness of the algorithm proposed was tested through comprehensive characterisation by studying eight weave patterns: plain, twill, weft satin, warp satin, basket, honeycomb, compound twill, and diamond twill and detecting fabric defects. Firstly, the main parameters such as dictionary size, patch size, and cardinality T were optimised, and then 40 defect-free fabric samples were characterised by the algorithm proposed. Subsequently, the Impact of the weave pattern was investigated based on the representation result and texture structure. Finally, defective fabrics were detected. The algorithm proposed is an alternative simple and scalable method to characterise fabric texture and detect textile defects in a single step without extracting features or prior information.

Trachyte reservoir characteristics and favorable reservoir identification and prediction in the J34 block, Eastern Sag

Ma Chenglong, Wu Ying, Gu Tuan, Zhang Bin, Li Yu Gang, Zhang Ying Jie, Dong Wen Bo, Cui Jie

Acta Geophysica

2022

Vol. 70, no 4

1635--1650

Influenced by tectonic activities such as the Tan-Lu Fault and mantle uplift, frequent volcanic activity in the Eastern Sag of the Liaohe Basin has resulted in the widespread development of volcanic rocks, such as basalt and trachyte, in the third member of the Shahejie Formation. Exploration and development have confirmed the presence of large oil and gas displays in trachyte reservoirs. However, previous studies have focused on the whole Eastern Sag or the volcanic rocks in the north, middle, and south sections of the Eastern Sag, while the J34 block has rarely been examined. There are challenges associated with the exploration and development of the J34 block, such as difficulties with trachyte lithology identification, reservoir space identification, quantitative logging identification, and prediction of horizontal and vertical distribution of lithologic characteristics. Therefore, this study presents an investigation and analysis of the characteristics of trachyte reservoirs, and the identification and prediction of favorable reservoirs based on core data, core sampling analysis, well logging, seismic data, and development dynamic data. The results showed that the volcanic rocks in the study area mainly include three types of lithology: trachytic breccia, trachytic lava, and basaltic lava, with trachytic breccia being the most important and favorable reservoir lithology. The trachyte reservoir space is mainly fractured and vuggy, and the secondary reservoir space is often superimposed onto the primary reservoir space, which significantly increases reservoir performance. Using the logging response characteristics of different lithologies and optimizing sensitivity curves, the quantitative identification criteria of different types of volcanic rocks were established. At the same time, the distribution characteristics of favorable reservoirs were determined by reconstructed wave impedance inversion with sensitive parameters, which showed that favorable reservoirs are mainly distributed along faults. Further analysis of the controlling factors of trachyte reservoirs can effectively guide the oil and gas development in this block and provide a reference for the exploration and development of similar blocks.