Research On Kink Effect In Output Curve Of Black Phosphorus Transistor

As the integration of electronic devices increases and high performance requirements increase,the size of field effect transistors shrinks,and the thermal effect of polysilicon thin film transistors is limited.Polysilicon thin film transistors are limited by thermal effects while silicon lacks dangling bonds due to the surface.Moreover,when the thickness of silicon is reduced to less than 5 nm,crystals of better quality silicon cannot be obtained,which makes the size reduction more difficult.Two-dimensional?2D?semiconductor material transistors such as graphene,molybdenum disulfide?MoS₂?,black phosphorus?BP?and other 2D semiconductor materials have attracted wide attention due to their nanometer-scale thickness,good quantum confinement,and few surface dangling bonds.Among them,BP has a unique band gap?0.3 eV².0 eV?which varies with thickness.The mobility of up to 1000cm² V^-1 S^-1 and its excellent electrical properties make it one of the hot materials.Exploring the electrical characteristics of BP transistors,understanding the operating mechanism of new semiconductor material transistors and improving the electrical performance of 2D transistors will not only help solve the dilemma faced by electronic device size reduction process,but also help BP transistors in optical sensing,flexible electronics,power devices and other aspects show better performance and unique advantages.As the device size continues to shrink close to its physical limit,the internal electric field strength of the transistor is correspondingly enhanced,and the avalanche breakdown of the two-dimensional transistor will seriously affect the performance and overall reliability of the device.In the research on the BP transistor,the output characteristic of the device has also been observed to exhibit an‘up-kick'in the saturation regime.Since the active layer of the material is exposed to high electric fields,it causes electrical breakdown.This neglected phenomenon has an important influence on the continuous development of two-dimensional materials.Moreover there is no detailed analysis and explanation of the electrical breakdown mechanism of the BP transistor.Through the comprehensive investigation of various channel thicknesses,channel lengths and operating temperatures,it is attributed such novel behavior to the kink effect originating from impact ionization and related potential shift inside the channel.Through the numerical simulation of the device,the influence of the geometric characteristics of the device on the potential distribution and current density in the channel is revealed,and the corresponding transportation mechanism is given,which shows a good consistency with the experimental phenomenon.After exploring the mechanism of the avalanche breakdown phenomenon of the BP transistors,the method of nitrogen?N₂?plasma treatment is carried out to eliminate the current anomalous increase and suppress the kink effect with improved saturation current.This work not only sheds light on the understanding of carrier transport within the BP transistor,but also could open up new potential for achieving high-performance and reliable electronic devices based on the 2D materials.