First Principle Study On The Band To Band Tunneling Of ?-? Semiconductor Materials

As developing of the semiconductors technology,new tunneling field effect transistors(TFETs)are being investigated as possible replacements for traditional metal-oxide-semiconductor field effect transistors(MOSFETs).Band-to-band tunneling(BTBT)in semiconductors has been discussed as a promising current injection mechanism to allow for reduced operating voltage for beyond MOSFET technology.III-V alloy semiconductors have been applied to promote performance of TFETs due to its excellent photoelectric properties.Based on density functional theory,this dissertation discusses the proposal of BTBT for the pure III-V semiconductors and the Ga/Sb doped III-V semiconductors in the tunneling region.When the same alloy martial is chosen in sourse,channel and drain region,the semiconductor with a smaller energy gap corresponds to the larger transmission coefficients and current.For the case of fixing the channel length,the bias also increases transmission coefficients and the current densities.Meanwhile,the TFETs with a shorter channel length show a larger current due to reducing the tunneling barrier.It indicates that the most effective way to enhance the tunneling is to reduce the band gap and the length of the tunneling region.Furthermore,the Ga/Sb atoms are doped in the tunneling region of a pure InAs structure.As we know,if the lattice constant of the whole system is chosen as that of the bulk InAs in the calculation,it is similar to add the strain of tension or compression in the tunneling region.The opposite results are contained comparing to the system with the same material in the soure,channel and drain region.Besides,it is found that the width of the doping region have an important effect on changing the transmission coefficients and the current densities.