This study reports the impact of forming gas annealing (FGA) on the electrical characteristics of sulfur passivated, atomic layer deposited Al2O3 gate dielectrics deposited on (110) oriented n- and p-doped In0.53Ga0.47 As layers metal-oxide-semiconductor capacitors (MOSCAPs). In combination, these approaches enable significant Fermi level movement through the bandgap of both n- and p-doped In0.53Ga0.47 As (110) MOSCAPs. A midgap interface trap density (Dit) value in the range 0.87−1.8×1012 cm−2eV−10.87−1.8×1012 cm−2eV−1 is observed from the samples studied. Close to the conduction band edge, a Dit value of 3.1×1011 cm−2eV−13.1×1011 cm−2eV−1 is obtained. These data indicate the combination of sulfur pre-treatment and FGA is advantageous in passivating trap states in the upper half of the bandgap of (110) oriented In0.53Ga0.47 As. This is further demonstrated by a reduction in border trap density in the n-type In0.53Ga0.47 As (110) MOSCAPs from 1.8×1012 cm−21.8×1012 cm−2 to 5.3×1011 cm−25.3×1011 cm−2 as a result of the FGA process. This is in contrast to the observed increase in border trap density after FGA from 7.3×1011 cm−27.3×1011 cm−2 to 1.4×1012 cm−21.4×1012 cm−2 in p-type In0.53Ga0.47 As (110) MOSCAPs, which suggest FGA is not as effective in passsivating states close to the valence band edge
In recent years two general methods for flow analysis in turbomachinery have been developed, one generally called the Streamline Curvature Method, the other the Matrix Through-Flow Method. Both methods solve the same flow equations but the differences in technique introduce different operational constraints and difficulties. A comparative assessment of the relative merits of the two methods has been difficult because the various authors did not use similar cascade models to represent cascade loss and deviation, a necessary adjunct to each technique. This paper outlines the two methods, and a common cascade model for both, and compares two programs written to implement the two techniques for ease of use, computer time and storage requirements, flexibility and inherent limitations. The programs are used to compute the flow field in three axial flow compressor applications: an interconnecting duct, a transonic fan, and three stage axial compressor. The predicted performance for the above machines was fairly good, although no attempt was made to “tune” the cascade model for the specific type of machine, as the relative merits of each method were of interest. It is concluded that there is a small operational advantage to the matrix method.
Based on current projections, III-Vs are expected to replace Si as the n-channel solution in FinFETs at the 7nm technology node. The realisation of III-V FinFETs entails top-down fabrication via dry etch techniques. Vertical fins in conjunction with high quality sidewall MOS interfaces are required for high-performance logic devices. This, however, is difficult to achieve with dry etching. Highly anisotropic etching required of vertical fins is concomitant with increased damage to the sidewalls, resulting in the quality of the sidewall MOS interface being compromised. In this work, we address this challenge in two stages by first undertaking a systematic investigation of dry etch processing for fin formation, with the aim of obtaining high resolution fins with vertical sidewalls and clean etch surfaces. In the second stage, dry etch process optimisation and post-etch sidewall passivation schemes are explored to mitigate the damage arising from anisotropic etching required for the realisation of vertical fins.
A major advantage of the two-shaft gas turbine as a prime mover is the steep torque-speed characteristic, so that the stall torque is typically twice the design torque. The co-turboshaft engine has a torque-speed curve which can be more than twice as steep as the conventional engine, so that only a rudimentary transmission would be required for normal operations. The co-turboshaft gas turbine engine has a co-rotating compressor case which is geared, together with the free power turbine, to the output shaft. As load increases and output shaft speed decreases, the effective gas generator speed increases, with no increase in rotor speed, and the power output rises. The engine has a torque-speed curve with up to four times the slope of a conventional free shaft turbine engine torque curve. This paper reviews results of testing a compressor with a co-rotating casing, and presents the results of simulating a typical engine using a hybrid computer to predict engine steady state performance. Effects of different design choices of compressor casing speed ratio are shown on engine torque, power and turbine inlet temperature characteristics. Control strategies for some possible applications, such as off-road vehicles and construction equipment, are discussed in relation to their likely duty cycles.
This paper reviews some recent activity at the James Watt Nanofabrication Centre in the University of Glasgow in the area of plasma processing for energy efficient compound semiconductor-based transistors. Atomic layer etching suitable for controllable recess etching in GaN power transistors will be discussed. In addition, plasma based surface passivation techniques will be reviewed for a variety of compound semiconductor materials ( (100) and (110) oriented InGaAs and InGaSb).
The stress required for the plastic deformation of a metal at elevated temperatures depends on both temperature and strain rate. In order to determine mechanical properties at high temperatures, both these quantities must be known and controlled. Otherwise stress cannot be expressed as a unique function of strain. The machine described in this paper performs short time tensile tests at constant temperature and constant true strain rate. It automatically measures and controls the minimum diameter of a cylindrical specimen which is pulled in a constant temperature furnace. A cam drive establishes the required exponential variation of diameter with time, and, by means of an optical comparator and error-operated servo, the testing machine pulls the specimen at the required rate. Load is determined by measuring the deflection of weigh-bars in series with the specimen. Since true strain increases linearly with time, a true stress, true strain curve can be plotted from yield to fracture.
The information obtainable with this machine should be of considerable value in hot-working research, and will complement that available from creep and stress rupture tests.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.