Charge characteristics of MOS structure with thermal SiO2 films doped with phosphorus under high-field electron injection

Positive flatband voltage shift in phosphorus doped SiO2/N-type 4H-SiC MOS capacitors under high field electron injection

“…These results are in good agreement with those reported previously for phosphorus doped SiO 2 /Si MOS capacitors [24,34]. Andreev, et al observed that the injected charge density depends on the thickness of the phosphorus-doped oxide with the accumulated negative charge density increasing with increasing phosphorus-doped SiO 2 film thickness [34]. Reports in literature have also shown that the stability of phosphorus-passivated 4H-SiC MOSFETs can be improved by reducing the thickness of the interfacial PSG gate dielectric layer [36].…”

“…As can be seen in figures 3(c) and (d), the shift in the flatband voltage and effective oxide charge increased, following a t 1/2 relation with bias stress time, suggesting there is a limit to the charge density that can be injected prior to oxide breakdown. These results are in good agreement with those reported previously for phosphorus doped SiO 2 /Si MOS capacitors[24,34]. Andreev et al observed that the injected charge density depends on the…”

“…In contrast the phosphorus-doped SiO 2 are shifted to the positive every time the measurement is repeated. The accumulation of negative charge in the gate dielectric shifts the I − V curves in a positive direction and increases the breakdown voltage by changing the charge state of the defects in the gate dielectric [34]. This effect can be explained by reducing the concentration of uncharged defects through the accumulation of a negative charge in the gate dielectric by increasing the amount of charge injected into the dielectric.…”

“…As reported in the literature, the effective oxide charge in MOS capacitors can be modified by the injection of electrons into the gate dielectric, which typically occurs at high electric field [34,35]. The probability of electron injection from the semiconductor to the gate dielectric or from the gate contact to the gate dielectric is increased at high temperatures because of potential barrier lowering and the number of electrons gaining sufficient energy to overcome the barrier height (so called hot electrons) [35].…”

“…Therefore, the increased leakage current in the undoped sample at 100 °C indicates a lower breakdown voltage, whilst the decreased leakage current in the P-doped sample suggests an increase in breakdown voltage with temper ature. The accumulation of negative charge in the PSG film, due to phosphorus atoms enhancing electron injection into the gate dielectric [12,34,42], leads to an increase in the energy barrier [39] at the injection interface boundary, which increases the breakdown voltage of the gate dielectric.…”