Threshold Voltage Shift and Its Turnaround of SiC MOSFETs Under Positive and Negative Oxide Electric Field Stresses (Invited)

Positive and negative bias temperature instabilities (PBTI and NBTI) in 4H-SiC MOSFETs are examined under a wide range of oxide electric field (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${{E}_{ox}}$</tex>) stress. The threshold voltage shift and its turnaround, observed under both highly positive and negative <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">${{E}_{ox}}$</tex> stresses, are evaluated. The latter is attributed to the impact of both electron and hole traps in the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{Si}{{\mathrm{O}}_2}$</tex> and/or near the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{Si}{{\mathrm{O}}_2}/\text{SiC}$</tex> interface. To physically understand these phenomena, it is important to analyze these contributions to the threshold voltage shift separately.