Cut-Off Degradation of Output Current Induced by High Fluence Neutron Radiation in High-Voltage Silicon-on-Insulator Lateral Double-Diffused MOSFET

Abstract

In this letter, a novel cut-off degradation of output current induced by high fluence neutron radiation is investigated for high-voltage silicon-on-insulator lateral double-diffused MOSFET (HV SOI LDMOS). Unlike low/middle fluence, severe current collapse occurs at low drain voltage. Combining experiments and energy band analysis, we reveal that a secondary charge removal effect leads to cut-off degradation, which is closely related to the field enhancement and high-density defects at high neutron fluence. Although the gate channel can be turned on after radiation, below drain threshold voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{V}_{\text {DT}}$ </tex-math></inline-formula> ), electron drift is blocked by a potential barrier caused by the local space charge region with low trap occupation rate, rather than the global impact at low fluence. In addition, the influences of structural parameters on the cut-off degradation and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{V}_{\text {DT}}$ </tex-math></inline-formula> are studied to guide the rad-hardening design of HV SOI LDMOS.