Carbon Nanotube Field Effect Transistors (CNTFETs) are being proposed as candidates for next-generation integrated circuit technology replacing conventional MOSFET devices. It is a suitable nanoelectronic device which is used for high speed and low power design applications which include analog and digital circuits. In this paper, a single wall carbon nanotube field effect transistor (SW-CNTFET) with a coaxial structure in the ballistic regime has been studied and its performance parameters discussed. Numerical simulations were performed based on Natori approach. The various device metrics in consideration are drive current (Ion), Ion/Ioff ratio, output conductance (gd), trans-conductance (gm), gain, carrier injection velocity, sub-threshold swing and drain induced barrier lowering (DIBL). In particular, the influences of gate oxide thickness on the short-channel effects are presented in detail. Also, the dependence of sub-threshold swing and DIBL on the gate control parameter has been discussed.

In this paper theoretical studies have been performed on a multijunction GaInP/GaAs based tandem solar cell. The top GaInP cell and the bottom GaAs cell were investigated separately. At an operating temperature of 300K, the current matching condition is fulfilled when the top cell and bottom cell base doping concentration and thickness are set to 5x1015/cm3, 1µm, and 2x1017/cm3, 0.127µm respectively. For the purpose of the investigation, a wide operating temperature range was chosen from 25ºC to 100ºC. The optimized tandem solar cell structure having a thickness of 1.847 microns is found to have VOC=2.2996V, ISC=0.0136Amp/cm2, FF=87.61% and ɳ=27.4% under AM1.5G one sun illumination. Studies have also revealed that when the cells are analyzed separately the current mismatch is less significant at low temperatures with the difference becoming notable at higher temperatures. Simulations of the solar cell were performed using PC1D.