Effect of Boron Incorporation on Slow Interface Traps in SiO2/4H-SiC Structures

The reason for the effective removal of interface traps in SiO2/4H-SiC (0001) structures by boron (B) incorporation was investigated by employing low-temperature electrical measurements. Low-temperature capacitance–voltage and thermal dielectric relaxation current measurements revealed that the density of electrons captured in slow interface traps in B-incorporated oxide is lower than that in dry and NO-annealed oxides. These results suggest that near-interface traps can be removed by B incorporation, which is considered to be an important reason for the increase in the field-effect mobility of 4H-SiC metal–oxide–semiconductor devices. A model for the passivation mechanism is proposed that takes account of stress relaxation during thermal oxidation

Insight into enhanced field-effect mobility of 4H-SiC MOSFET with Ba incorporation studied by Hall effect measurements

Improved performance in 4H-SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) by incorporating Ba into insulator/SiC interfaces was investigated by using a combination of the Hall effect and split capacitance-voltage measurements. It was found that a moderate annealing temperature causes negligible metal-enhanced oxidation, which is rather beneficial for increments in field-effect mobility (μFE) of the FETs together with suppressed surface roughness of the gate oxides. The combined method revealed that, while severe μFE degradation in SiC-MOSFETs is caused by a reduction of effective mobile carriers due to carrier trapping at the SiO2/SiC interfaces, Ba incorporation into the interface significantly increases mobile carrier density with greater impact than the widely-used nitrided interfaces

Electrical detection of TV2a-type silicon vacancy spin defect in 4H-SiC MOSFETs

Color centers in silicon carbide (4H-SiC) are potentially usable as spin defects for quantum sensing and quantum information technology. In particular, neutral divacancies (the P6/P7centers, VSiVC 0) and a certain type of silicon vacancies (the TV2a center, VSi - at the k site) are promising for addressing and manipulating single spins. Although the TV2a spin is readable at room temperature, the readout techniques have been limited to luminescence-based ones (e.g., optically detected magnetic resonance). In this study, we demonstrated electrical detection of TV2a-type silicon vacancies at room temperature by using electrically detected magnetic resonance on 4H-SiC metal–oxide–semiconductor field effect transistors (MOSFETs). TV2a spin defects were embedded in the channel region of well-defined 4H-SiC MOSFETs via controlled proton irradiation. The number of detected TV2a spins was estimated to be 10^5. We also found that the charge state of the TV2aspin defect can be controlled by varying the gate voltage applied to the MOSFET

Insight into enhanced field-effect mobility of 4H-SiC MOSFET with Ba incorporation studied by Hall effect measurements

Improved performance in 4H-SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) by incorporating Ba into insulator/SiC interfaces was investigated by using a combination of the Hall effect and split capacitance-voltage measurements. It was found that a moderate annealing temperature causes negligible metal-enhanced oxidation, which is rather beneficial for increments in field-effect mobility (μFE) of the FETs together with suppressed surface roughness of the gate oxides. The combined method revealed that, while severe μFE degradation in SiC-MOSFETs is caused by a reduction of effective mobile carriers due to carrier trapping at the SiO2/SiC interfaces, Ba incorporation into the interface significantly increases mobile carrier density with greater impact than the widely-used nitrided interfaces

Energy levels of carbon dangling-bond center (PbC center) at 4H-SiC(0001)/SiO2 interface

The electric properties of the carbon dangling-bond (PbC) center at a thermally oxidized 4H-SiC(0001)/SiO2 interface are investigated. We experimentally and theoretically determine the energy levels of the associated interface states to estimate the impacts of the PbC center on power device operations. By combining electrically detected magnetic resonance spectroscopy and capacitance–voltage measurements, the two PbC electronic levels [(0/−) and (+/0)] are determined as ∼1.2 and 0.6 eV from the valence band maximum, respectively. The effective correlation energy of the PbC center is 0.6 eV, which is 1.5 times larger than that of the silicon dangling-bond (Pb) center at Si/SiO2 interfaces. Our first-principles calculations confirm that the electronic levels of PbC are similar to experimental values. Considering these energy levels, the PbC center must impact both p- and n-channel devices, which is closely related to previously reported channel features