The Carrier Capture And Emission Properties Of Silicon Interstitial Defects In Near Interface Region Of SiC/SiO₂

As the third generation semiconductor material,silicon carbide?SiC?has superior theoretical and physical properties,but the actual metal-oxide-semiconductor field-effect transistor?MOSFET?performance is not ideal.The bad interface characteristics caused by defects seriously affect the performance of devices.In particular,the defects near the interface introduce a density of states of 10¹33 cm^-2eV^-1 near the 0.2 eV of SiC conduction band.The traps formed by these defects are called by near interface oxide traps?NIOTs?which are considered to be the main factors affecting the device stability.As the origin of the near interface traps in SiC/SiO₂ system,Si interstitial defects need to be further studied.In this work,?-SiO₂ and amorphous SiO₂ models are established based on density functional theory to investigate the carrier capture and emission properties of Si interstitial defects with two different configurations in near interface region on the SiO₂ side.Based on the simulation results,the influence and mechanism of defects on the device stability are discussed.According to the defect models,silicon interstitial defects can be divided into Si–Si–Si configuration and Si–Si–O configuration,in which the formation energy of Si–Si–Si configuration is lower and the corresponding structure is more stable.Calculation results indicate that the Si–Si–Si configuration has a strong capture ability for holes but weak capture ability for electrons,while the Si–Si–O has a strong ability to capture both holes and electrons,which makes these two configurations affect the stability of p-channel and n-channel MOS devices in different degrees.In addition,the wide O–Si–O bond angle caused by amorphous environment has a strong electron capture ability,which usually appears in the SiO2tetrahedron or Si–Si–Si configuration,and can be considered as the main defect configuration affecting the stability of n-channel MOS devices.For the charge emission ability,the Si–Si–Si configuration has strong emission ability for both electrons and holes.Therefore,the traps can exchange charges with the channel and thereby affect the stability.While Si–Si–O has a strong ability to emit electrons but weak ability to emit holes,which makes the hole trap act as a fixed positive charge,affecting device mobility.For the defects with wide O–Si–O bond angle,most of the negative center have weak electron emission ability,thus these traps will affect the mobility in the form of fixed negative charge through Coulomb scattering.This work is helpful to understand the mechanisms of the deterioration in reliability caused by SiC near-interface oxide defects.