Study On Synthesis Of Black Arsenic Phosphorus Material Reinforced By Exogenous Gas Phase Molecules

Black arsenic phosphorus（b-AsP）two-dimensional materials have excellent characteristics such as moderate tunable band gap,high theoretical carrier mobility and anisotropy,and have great application potential in infrared detectors,lasers,lithium ions/solar cells,etc.At present,the synthesis of b-AsP materials by gas phase method lacks systematic exploration,and its reaction mechanism is still unclear,which leads to the lack of theoretical guidance for material synthesis and the large fluctuation of material quality.Therefore,the gas phase synthesis mechanism and systematic research of b-AsP need to be broken through.In view of this situation,this study carried out a systematic research on the synthesis of b-AsP by chemical vapor transport（CVT）.Through density functional theory（DFT）simulation and experimental verification,the law of crystal phase transformation of b-AsP regulated by exogenous molecules was explored for the first time,and a new route for the synthesis of b-AsP was put forward.Furthermore,the representative exogenous molecule was selected to optimize the growth of the materials.By using the fewlayer nanosheet peeled from the synthesized bulk b-AsP,the oxidation resistance of b-AsP synthesized under different exogenous molecules regulation and the carrier transmission characteristics of the few-layer black arsenic phosphorus field effect transistors（FETs）were investigated.The main research contents and conclusions of this reserch are as follows:（1）The experiment of synthesizing b-AsP by exogenous monatomic molecules/molecules of nonmatals regulation such as iodine（I）,chlorine（Cl₂）and bromine（Br₂）was designed,which proved that exogenous molecules of nonmatals could promote the crystal phase transformation of b-AsP.Different from the transformation ideas of Sn IP or Au₃SnP₇ key intermediates reported in the existing literature,a new path of"exogenous molecules reduce crystal energy through surface adsorption,and realize stable transformation of b-AsP crystal phase"is put forward.The optimization of the growth conditions of b-AsP under the regulation of I exogenous molecules was carried out.It was found that the high-efficiency crystal phase transformation of b-AsP could be realized under the regulation of I,and the reaction time could be greatly reduced to 14 h compared with the dozens of hours in the existing system.（2）The research on the enhancement of b-AsP synthesis by exgenous metal monatomic molecules such as antimony（Sb）,tin（Sn）,lead（Pb）,bismuth（Bi）and tellurium（Te）has been carried out,and it has been revealed that exgenous metal molecules of different metals have stronger effect of promoting the crystal phase transformation of b-AsP.The new route proposed in this research was further verified,and the growth of crystal materials is optimized.The optimization of growth conditions of b-AsP under the reaiforce of Sn was carried out,and the silver-gray bulk b-AsP crystal with high purity,superior crystal form and single（010）crystal plane family growth trend was obtained.（3）Aiming at the subsequent application of the materials,the properties of b-AsP materials synthesized by different exogenous molecules regulation were investigated.In terms of oxidation resistance,it was found that the order of oxidation resistance of different materials wasb-AsPexogenous metal molecule regulation≥b-AsPexogenous molecule of nonmetals regulation>commercially available black phosphorus（BP）>gray arsenic（g-As）,and the b-AsP regulated by Pb had the best antioxidant capacity.In terms of the carrier transmission characteristics of FETs,it is found that the black arsenic phosphorus FETs synthesized by Sb,Sn,Pb,Bi,Te and other molecules regulation under the condition of low bias voltage（Vds）show obvious bipolar in the gate voltage range of-40 V～40 V;The black arsenic phosphorus FETs synthesized by I molecule regulation show obvious N-channel effect.Among them,b-AsP FETs synthesized by Sn molecule regulation have the highest carrier mobility,about 231.64 cm²V^-1s^-1,and I molecule has the lowest,about 63.83 cm²V^-1s^-1.The measured switching ratio of b-AsP FETs synthesized by different exogenous molecules regulation is 1.03～2.38;All the b-AsP field-effect transistors synthesized by exogenous molecules regulation except Te show obvious gate-controlled adjustment ability.