Experimental and Numerical Investigation of Gaseous Detonation in a Narrow Channel with Obstacles

Gaseous detonation propagation in a thin channel with regularly spaced cylindrical obstacles was investigated experimentally and numerically. The wave propagation with substantial velocity deficits is observed and the details of its propagation mechanism are described based on experimental measurements of the luminosity and pressure and on three-dimensional flow fields obtained by numerical simulations. Both experiments and simulations indicate a significant role of shock–shock and shock–obstacle interactions in providing high-temperature conditions necessary to sustain the reaction wave propagation.

Simulation Study of the Impact of Traps in GaN Substrates on the Electrical Characteristics of AlGaN/GaN HEMTs with Thin Channel Layers

GaN substrates are promising candidates for GaN high electron mobility transistors (HEMTs) due to their epitaxial layer growth with a low defect density. In this study, technology computer-aided design simulations were executed to design the GaN HEMTs on semi-insulating GaN substrates with thin channel layers. Traps in the GaN substrates played a role in suppressing drain-leakage currents, although degrading transient responses changed the bias from off to on-state for the 0.02-μm thin channel layer. A trade-off relationship between the drain-leakage current and transient response is occurred by changing the trap concentration in the GaN substrates. The AlGaN back-barrier structure has been found to be highly effective in suppressing the drain-leakage current in low-trap-concentration GaN substrates. The trade-off relationship improved by adopting the back-barrier layers, and the maximum drain current decreased. The drain-current reduction compensated by increasing the Al content in the barriers without degrading the trade-off relationship. Therefore, for GaN HEMTs that have low-trap-concentration GaN substrates combined with the back-barrier layer, a high-Al-content barrier have characteristics that are favorable for the trade-off relationship in the case of thin channel layers. Moreover, the traps in GaN substrates were found to affect low-frequency S 21 , which is important for linearity of the power amplifier, as critically as the transient responses.

Chemistry of Photo Isomerization and Thermal Reset of Nitro-Spiropyran and Merocyanine Molecules on Channel of MoS2 Field Effect Transistor

We explore the chemical reaction of the photo isomerization and thermal reaction of photochromic spiropyrans (SP) (1′,3′-Dihydro-1′,3′,3′-trimethyl-6-nitrospiro[2H-1-benzopyran-2,2′-(2H)-indole] molecule deposited on atomically thin channel of MoS2 for field effect transistor (FET)...