Power semiconductor devices are key components in power conversion systems. Silicon carbide (SiC) has received increasing attention as a wide-bandgap semiconductor suitable for high-voltage and low-loss power devices. Through recent progress in the crystal growth and process technology of SiC, the production of medium-voltage (600?1700 V) SiC Schottky barrier diodes (SBDs) and power metal?oxide?semiconductor field-effect transistors (MOSFETs) has started. However, basic understanding of the material properties, defect electronics, and the reliability of SiC devices is still poor. In this review paper, the features and present status of SiC power devices are briefly described. Then, several important aspects of the material science and device physics of SiC, such as impurity doping, extended and point defects, and the impact of such defects on device performance and reliability, are reviewed. Fundamental issues regarding SiC SBDs and power MOSFETs are also discussed.

https://iopscience.iop.org/article/10.7567/JJAP.54.040103/pdf

Material science and device physics in SiC technology for high-voltage power devices

Preferential diffusion of various gases down the grain boundaries in polycrystalline silicon is shown to promote significant changes in the density of defect states in these regions. A plasma of monatomic hydrogen provides a significant reduction in both the state density and the accompanying grain‐boundary potential barrier while plasmas of oxygen, nitrogen, and sulfur hexafluoride are shown to increase this density of states. Boundaries passivated with hydrogen have as much as a factor of 1000 larger transconductance after treatment. Hydrogenated barriers are stable over long periods at 375 °C and essentially indefinitely at 23 °C. The results have important implications for the development of low‐cost thin‐film silicon photovoltaic devices.

Passivation of grain boundaries in polycrystalline silicon

We have characterized the electrical transport properties of neutron‐transmutation‐doped polycrystalline silicon. Zero‐bias measurements of resistance have been made as a function of temperature on both bulk specimens and individual grain boundaries in this material. Below a doping level of ∼2×1015 phosphorus/cm3, the bulk resistance has a nearly Arrhenius behavior with an activation energy of ∼0.55 eV; above this donor concentration the resistivity is markedly curved on an Arrhenius plot with values of slope which decrease with decreasing temperature. Potential probe measurements show that a large spread in grain‐boundary impedances exist in these higher‐doped specimens. We compare our data to theoretical expressions for current flow across grain‐boundary potential barriers and good agreement is observed; these comparisons indicate that the largest grain‐boundary state densities observed in our samples consist of ∼6×1011 available single‐electron‐states/cm2 located within ∼0.2 eV from the center of the f...

Zero‐bias resistance of grain boundaries in neutron‐transmutation‐doped polycrystalline silicon

Zero-bias resistance of grain boundaries in neutron transmutation doped polycrystalline silicon

Experiments and theories concerning charged dislocations in alkali halide crystals are reviewed in detail, with particular attention to the way in which the experiments should be interpreted and to the range of applicability of the sweep-up and various forms of thermal-equilibrium models. Possible effects on mechanical properties and internal friction are analysed. The transient and steady-state effects of plastic deformation on ionic conductivity are described and new interpretations involving charged dislocations are proposed. A survey of results on the scattering of light by alkali halide single crystals leads to the conclusion that charged dislocations do not play an important role. Evidence about charges on surfaces and on dislocations in AgCl and AgBr is reviewed and compared with that for alkali halides. Comparisons are also made with MgO, the CsCl and CaF2 structures, semiconductors and ice.

Charged dislocations in ionic crystals

https://iopscience.iop.org/article/10.1149/1.2404420/pdf

E. Kostiner

Papers

Defect electronics in semiconductors