Strain Engineering On Black Phosphorus With Adsorbed Iron Atom And Its Performances Of Gas Sensor

Black phosphorus has an adjustable direct band gap and high carrier mobility,which makes up for the deficiency of graphene and transition metal sulfides,and thus has attracted more and more attentions of researchers.However,the instability in environmental conditions of BP seriously hampered its applications.Metal atom adsorption is considered to be an efficient approach to achieve stability of black phosphorus required by practical devices with no damage to its pristine excellent properties.The adsorption of Fe atom not only improves the environmental stability of black phosphorus,but also further enrich its electronic properties,which could be further regulated by applying strain.The gas sensor based on the stable Fe@BP systems would be a candidate material for gas sensor with high sensitivity and identification.In this paper,the strain engineering of Fe adsorbed BP and its potential applications in gas sensors are studied by using first-principles calculation methods.The main contents are as follows:1.The structures model of transition metal Fe atom adsorbed monolayer BP were constructed and the electronic properties of the adsorption systems were studied.And the strain effects on the electronic properties of Fe@BP system are investigate.The results show that the adsorption of Fe atom reduces the band gap value of BP,and the adsorption system becomes an indirect band gap semiconductor concurrently.In addition,the environmental stability of BP is improved for the bottom of the valence band of the adsorption system is lower than the redox potential after adsorption.The compressive strain reduces the band gap value of the adsorption systems,and eventually results in a semiconductor-metal transition when the strain reaches-8%.The tensile strain turns the value of band gap ranging from 0.96 e V to 0.60 e V,and an indirect-direct band gap transition would occur with the tensile strain of 4%.The research provides some guidance and support for the nanometer devices based on monolayer BP with environmental stability and adjustable electronic properties.2.Considering the advantage of 2D black phosphorus in detecting gas molecules,the gas sensitive performances of Fe@BP monolayer were explored.Compared with the original monolayer BP,it is found that the adsorption of transition metal Fe atoms changes the adsorption energy,charge transfer and electronic properties of the gas on BP,thus affecting the change of the resistivity,which is shown as the enhancement of the sensitivity of the gas sensor based on black phosphorus.We also studies the change of gas sensitivity and electronic properties of Fe@BP system under different strains.The results show that it is highly dependent on strain,and different gas molecules have different change trends.With the increasing of the compression strain,the band gap values of the three gas molecules are all decrease continuously.When the compressive strain reaches-6%,the band gap values of NO₂ and NO adsorption systems show metallic properties due to the CBM passing through the Fermi level,while the CO adsorption system still maintains semiconductor properties.For the adsorption systems of NO molecular,when the applied compression strain reaches-5%,the original spin polarized band gaps occurs overlap.The research are expected to provide ideas and theoretical support for the strain-dependent gas sensor based on Fe@BP with high sensitivity and identification.