N-type and P-type Co-doping for optimizing Turn on and Threshold field of SiC towards enhanced field emission property

Abstract

Turn on field (Eto) and Threshold electric field (Ethr) are regarded as typical indexes for fabricating the better field emission (FE) devices. Although doping as the efficient strategy to enhance its FE properties, the reasons for the effect of various type dopant on Eto and Ethr values is unrevealed. In this paper, Lanthanum (p-type) and Nitrogen (n-type) Co-doped SiC nanowires (LN-SiC NWs) prepared using the two steps method, and it delivers the enhanced FE properties with reduced Eto and Ethr values of 0.938 V/μm and 3.077 V/μm, respectively. Series of characterizations and DFT calculation results reveal the internal reasons for the enhanced FE properties by n-type and p-type dopant co-doping. Eto value is influenced by the total emission electrons amount, and n-type N doping owning more valence electrons could provide more charge carriers for CB to increase it, therefore, n-type N doping could reduce Eto value on the one hand. Ethr value is influenced by the band gap, and n-type N doping and p-type La doping could alter the hybridizations states of CB and VB for narrowing the band gap, therefore, n-type and p-type co-doping could enhance the FE properties of LN-SiC NWs. This work give the theoretical guiding for understanding the enhanced FE property as well as the effect of dopant type on reduced Eto and Ethr values.