More trading is algorithmic or computer generated, and in markets where it is allowed, high frequency. However, what happens when there is an algorithmic trading error? This study attempts to answer that question by examining the August 16, 2013, fat-finger trade in Chinese equity and equity futures markets. We find that both markets were excessively volatile, illiquid, and positively skewed. Moreover, we document that index returns are predictable for a shorttime, indicating that the fat-finger event induced an inefficient market. Our results highlight the importance of market surveillance and regulation to lessen the damage of future fat-finger events.
Ultrasmooth perovskite thin films are prepared by a solution-based one-step micro-flowing anti-solvent deposition (MAD) method carried out in air with simplicity and practicability. Engaging inert gas blow and anti-solvent drips as accelerators, ultrafast crystallizing, thickness controllable, and high quality methylammonium lead iodide films are prepared with a least root mean square roughness of 1.43 nm (1.95 nm on average), achieving the smoothest surface morphology to the best of our knowledge, as well as a rather compact perovskite layer with a high coverage ratio. Perovskite films formed from MAD require no annealing procedure to ultimately crystallize, realizing a very fast crystallizing procedure within few seconds. By controlling the thickness of perovskite films, superior photovoltaic performance of solar cells with a large fill factor of 0.8 and a PCE of 15.98% is achieved without a glovebox. MAD technology will benefit not only highly efficient photovoltaic devices, but also perovskite-based hybrid optoelectronic devices with field effect transistors and light emitting diodes as well.
In this letter, a plasma-free etch stop structure is developed for GaN HEMT toward enhancement-mode operation. The self-terminated precision gate recess is realized by inserting a thin AlN/GaN bilayer in the AlGaN barrier layer. The gate recess is stopped automatically at the GaN insertion layer after high-temperature oxidation and wet etch, leaving a thin AlGaN barrier to maintain a quantum well channel that is normally pinched off. With addition of an Al2O3 gate dielectric, quasi normally OFF GaN MOSHEMTs have been fabricated with high threshold uniformity and low ON-resistance comparable with the normally ON devices on the same wafer. A high channel mobility of 1400 cm(2)/V . s was obtained due to the preservation of the high electron mobility in the quantum-well channel under the gate.