Study Of Polarization-induced Doping InN-based Tunnel FETs

At present,reducing the power consumption of nano-integrated circuits has been the focus of research and attention at domestic and overseas.Many new low-power consumption semiconductor devices stand out,and the tunnel field effect transistors(TFETs)have attracted extensive attention as a kind of promising candidates.Compared with the conventional MOSFET,the superiority of TFETs lies in steeper subthreshold swing(SS)(SS<60 mV/decade),lower OFF-state leakage current and effective suppression of short channel effects(SCEs).However,there still exist many obstacles during the application of the conventional physical doping TFETs,such as the high thermal budget and expensive annealing techniques due to ion-implantation,and the random dopant fluctuation(RDF),which needs to be solved urgently.In order to solve these practical problems caused by traditional physical doping,based on the unique polarization effect of nitride,horizontal and vertical polarization-induced doping InN-based TFET devices are proposed and investigated by two-dimensional numerical simulations,and some research achievements and laws with practical application value have been obtained.The main research work and achievements are as follows:A polarization-induced doping InN-based TFET(PI-InN TFET)with overlapping-gate is proposed.The proposed device features the formation of P-type source and N-type drain induced by the polarization effect near the InN-based heterojunctions without the need for any physical doping,which makes it possible for the PI-InN TFET to avoid the random dopant fluctuation(RDF)and the problems related to the high thermal annealing techniques.The relationships between the structural parameters of the TFET device and the on-state current,subthreshold swing,as well as bipolar leakage current are studied systematically.Compared with the traditional physical doped InN-based TEFT device,the new device has more advantages in electrical characteristics,the average sub-threshold swing of the device is 33mV/dec,and I_on/I_off is 3.3×10¹².A Schottky source-drain polarization-induced doping InN-based TFET(SSD PI-InN TFET)is proposed and studied.By changing the work function of the electrode of source and drain and the size of the source-drain region,the on-state current and subthreshold swing are significantly improved,the average subthreshold swing of the device is 13.4mV/dec,I_on/I_off is 2.5×10¹⁵,and the bipolar leakage current of the device is suppressed by introducing InN/InGaN heterojunction in the channel,which does not affect the forward DC characteristics of the device.A vertical polarization-induced doping InN-based TFET(V-PI-InN TFET)is proposed.The correlation between the DC characteristics of the device and the structural parameters of the device is studied by two-dimensional numerical simulation.Compared with the polarization-induced doping InN-based TFET device,the average subthreshold swing of the device is reduced by about 29%,and I_on/I_off is improved by nearly four orders of magnitude.Finally,a vertical polarization-induced doping InN-based TFET device(V-PI-InN-HG-UC TFET)with hetero-gate and U-channel is proposed.By introducing U-channel and hetero-channel in the device,the performance of the device is improved dramatically.The average subthreshold swing is 7.0mV/dec,the on-state current is 2×10^-4A/?m,and I_on/I_offis about 2×10¹³.