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

The use of micro-Raman spectroscopy to monitor non-invasively GaN, AlGaN and AlN material parameters for process and growth monitoring/control is demonstrated. Concepts to determine the crystalline quality, the stress, the free carrier concentration, the aluminium composition and the temperature from the Raman modes are reviewed. Raman monitoring of processing and growth is illustrated on selected examples: the high-temperature processing of ion-implanted and non-implanted GaN layers, the Raman monitoring of AlGaN/GaN heterostructure field-effect transistors and the in situ Raman monitoring of GaN growth at elevated temperatures. Ultraviolet Raman spectroscopy has been employed to characterize material properties of GaN surface layers and GaN/AlGaN interfaces. Raman mapping is illustrated on bulk AlN crystals to investigate stress fields related to growth striations and defects. Copyright © 2001 John Wiley & Sons, Ltd.

Raman spectroscopy of GaN, AlGaN and AlN for process and growth monitoring/control

We report on the first planar high-voltage MOSFET's in 6H-SiC. A double-implant MOS (DIMOS) process is used. The planar structure ameliorates the high-field stressing encountered by SiC UMOS transistors fabricated by other groups. Blocking mode operation of up to 760 V is demonstrated, which is nearly three times higher than previously reported operating voltages for SiC MOSFET's.

High-voltage double-implanted power MOSFET's in 6H-SiC

Single-crystal nanotubes are commonly observed, but their formation is often not understood. We show that nanotube growth can be driven by axial screw dislocations: Self-perpetuating growth spirals enable anisotropic growth, and the dislocation strain energy overcomes the surface energy required for creating a new inner surface forming hollow tubes spontaneously. This was demonstrated through solution-grown zinc oxide nanotubes and nanowires by controlling supersaturation using a flow reactor and confirmed using microstructural characterization. The agreement between experimental growth kinetics and those predicted from fundamental crystal growth theories confirms that the growth of these nanotubes is driven by dislocations.

https://science.sciencemag.org/content/sci/328/5977/476.full.pdf

Mechanism and Kinetics of Spontaneous Nanotube Growth Driven by Screw Dislocations

Nanoscience and nanotechnology impact our lives in many ways, from electronic and photonic devices to biosensors. They also hold the promise of tackling the renewable energy challenges facing us. However, one limiting scientific challenge is the effective and efficient bottom-up synthesis of nanomaterials. We can approach this core challenge in nanoscience and nanotechnology from two perspectives: (a) how to controllably grow high-quality nanomaterials with desired dimensions, morphologies, and material compositions and (b) how to produce them in a large quantity at reasonable cost. Because many chemical and physical properties of nanomaterials are size- and shape-dependent, rational syntheses of nanomaterials to achieve desirable dimensionalities and morphologies are essential to exploit their utilities. In this Account, we show that the dislocation-driven growth mechanism, where screw dislocation defects provide self-perpetuating growth steps to enable the anisotropic growth of various nanomaterials at ...

Screw dislocation driven growth of nanomaterials.

Experimental studies on aluminum (Al) and boron (B) implantation in 4H/6H SiC are reported; the implantation is conducted at room temperature or elevated temperatures (500 to 700 C). Both Al and B act as ``shallow`` acceptors in SiC. The ionization energy of these acceptors, the hole mobility and the compensation in the implanted layers are obtained from Hall effect investigations. The degree of electrical activity of implanted Al/B atoms is determined as a function of the annealing temperature. Energetically deep centers introduced by the Al{sup +}/B{sup +} implantation are investigated. The redistribution of implanted Al/B atoms subsequent to anneals and extended lattice defects are monitored. The generation of the B-related D-center is studied by coimplantation of Si/B and C/B, respectively. (orig.) 60 refs.

Doping of SiC by Implantation of Boron and Aluminum

Micropipes are hollow tubular defects penetrating SiC single crystals. Different mechanisms of formation and stabilization as well as energetic aspects are discussed.

Micropipes : Hollow tubes in silicon carbide

Electrical properties of silicon carbide polytypes

Micropipes are hollow-core dislocations aligned along the growth direction of sublimation grown SiC ingots. We found micropipes nucleated in the interface region between the seed crystal and the grown ingot adjacent to stacking fault clusters on tilted closed packed planes. A relation between the edge and the screw component of the dislocation in the micropipe is derived.

J. Heindl

Papers

Doping of SiC by Implantation of Boron and Aluminum

Micropipes : Hollow tubes in silicon carbide

Electrical properties of silicon carbide polytypes

The nucleation sites of micropipes in SiC