Study On Structure And Characteristics Of InP-Based FinFET

Terahertz(THz)waves shows great application prospects and potentials in imaging,detection,communication and so on,due to the unique characteristics that because it’s in the transition region between the scope of electronics and photonics research.In Al As/In Ga As High Electron Mobility Transistor(HEMT)has become one of the most promising device in the field of THz low noise amplifiers and circuits because of its high gain,high cut-off frequency and low noise whiceowing to its unique material properties,and.At present,the international study on InP-based HEMT mainly focuses on the optimization of electrode ohmic contact and the composite channel structure,however,in order to improve the cutoff frequency of the device,the gate length has entered the nanometer range result in the short channel effects are starting to become non-negligible.To solve the problem of device performance degradation caused by Si-based complementary metal-oxide-semiconductor(CMOS)short-channel effects,a three-dimensional fin-gate(Fin)structure that utilizes the additional gate control capability provided by side gates is proposed.Therefore,this thesis focuses on the generation mechanism of the short channel effect,and studies the structure and characteristics of the InP-based FinFET device.Considering the unique channel carrier distribution of the double Si δ-doped device,Which make it has the advantages of higher output power and better frequency performance than the single-doped device,and because the double Si δ-doped device can be make better use of the gate control ability of the side gate,so this thesis adopts the Fin structure combined with the double Si δ-doped device structure to suppress the short-channel effect of the device and improve the transconductance peak drop,threshold voltage drift and subthreshold swing.At the same time,a higher transconductance boost is used to ameliorate the damage on the frequency performance.In this thesis,the Silvaco TCAD platform is used to model three-dimensional conventional InP-based HEMTs and FinFET devices,and analyzed that the mechanism of the shortchannel effect of conventional InP-based HEMTs is the decreasing of the gating ability caused by the reduction of the vertical expansion of the potential field under the gate.Then,the DC characteristics and frequency characteristics of the InP-based FinFET device under different Fin widths are simulated,the results show that the lateral electric field provided by the Fin structure has a good effect on ameliorate the short channel effect of the device,and the cut-off frequency of the device decrease along with Fin narrowing.Compared with conventional devices,when the Fin width is 200 nm,the absolute value of threshold voltage decreases by 65%,the peak value of transconductance increases by 42.6%,and the subthreshold swing decreases by 35%.When the Fin width is 500 nm,the cut-off frequency of the FinFET decreases by 14.2% compared with the conventional device,and when the Fin width is 200 nm,it decreases by 16.2%.At the same time,considering the effect of gate length on the device frequency performance,the frequency characteristics of FinFET devices under different gate lengths were studied.The results show that the amplitude of cut-off frequency increase with the shortening of the gate length,which has becomes smaller compared with the conventional device,caused by the additional parasitic capacitance from the side gate.When the gate length is 20 nm,the cut-off frequency of the FinFET device decreases by 20.1% compared with the conventional device.Next,in order to take advantage of the gate control capability of the side gate,the DC and AC characteristics of double Si-doped InP-based FinFET devices with different Fin widths were simulated and studied.When the Fin width was 100 nm,the absolute value of the threshold voltage decreased by 74%,and the the conduction peak is increased by 143%,the drain-induced barrier reduction effect is reduced by 93%,and the sub-threshold swing is reduced by 62.5%.The simulation results show that the Fin structure has a great ameliorate on the short channel effect of conventional double Si-doped InP-based HEMT devices.Moreover,the control of the carriers under the channel by the side gate produces a greater increase in transconductance,so that the frequency characteristic of the double-doped FinFET device is only 5.2% decline compared with the conventional double-doped HEMT device when the gate length is 50 nm.Finally,considering the influence of the thickness of the insulating layer under the gate on the gate capacitance of the device,the AC and DC characteristics of the device under different insulating layer thicknesses were analyzed.There is a certain improvement,but because the thickness of the insulating layer mainly affects the gate control ability of the side gate,the amplitude increasing is faint,and the frequency characteristics of the device hardly change with the thickness of the insulating layer.