The present disclosure relates to methods of fabricating a porous structure, such as a porous silicon carbide structure. The methods can include a step of providing a structure to be rendered porous, and a step of providing an etching solution. The methods can also include a step of electrochemically etching the structure to produce pores through at least a region of the structure, resulting in the formation of a porous structure. The morphology of the porous structure can be controlled by one or more parameters of the electrochemical etching process, such as the strength of the etching solution and/or the applied voltage.

The present disclosure relates to methods of fabricating a porous structure, such as a porous silicon carbide structure. The methods can include a step of providing a structure to be rendered porous, and a step of providing an etching solution. The methods can also include a step of electrochemically etching the structure to produce pores through at least a region of the structure, resulting in the formation of a porous structure. The morphology of the porous structure can be controlled by one or more parameters of the electrochemical etching process, such as the strength of the etching solution and/or the applied voltage.

The present disclosure relates to methods of fabricating a porous structure, such as a porous silicon carbide structure. The methods can include a step of providing a structure to be rendered porous, and a step of providing an etching solution. The methods can also include a step of electrochemically etching the structure to produce pores through at least a region of the structure, resulting in the formation of a porous structure. The morphology of the porous structure can be controlled by one or more parameters of the electrochemical etching process, such as the strength of the etching solution and/or the applied voltage.

The present disclosure relates to methods of fabricating a porous structure, such as a porous silicon carbide structure. The methods can include a step of providing a structure to be rendered porous, and a step of providing an etching solution. The methods can also include a step of electrochemically etching the structure to produce pores through at least a region of the structure, resulting in the formation of a porous structure. The morphology of the porous structure can be controlled by one or more parameters of the electrochemical etching process, such as the strength of the etching solution and/or the applied voltage.

High capacity silicon based anode active materials are described for lithium ion batteries. These materials are shown to be effective in combination with high capacity lithium rich cathode active materials. Supplemental lithium is shown to improve the cycling performance and reduce irreversible capacity loss for at least certain silicon based active materials. In particular silicon based active materials can be formed in composites with electrically conductive coatings, such as pyrolytic carbon coatings or metal coatings, and composites can also be formed with other electrically conductive carbon components, such as carbon nanofibers and carbon nanoparticles. Additional alloys with silicon are explored.

High capacity silicon based anode active materials are described for lithium ion batteries. These materials are shown to be effective in combination with high capacity lithium rich cathode active materials. Supplemental lithium is shown to improve the cycling performance and reduce irreversible capacity loss for at least certain silicon based active materials. In particular silicon based active materials can be formed in composites with electrically conductive coatings, such as pyrolytic carbon coatings or metal coatings, and composites can also be formed with other electrically conductive carbon components, such as carbon nanofibers and carbon nanoparticles. Additional alloys with silicon are explored.

GaN wafers and bulk crystal have dislocation density approximately 1/10 of dislocation density of seed used to form the bulk crystal and wafers. Masks are formed selectively on GaN seed dislocations, and new GaN grown on the seed has fewer dislocations and often 1/10 or less of dislocations present in seed.

GaN wafers and bulk crystal have dislocation density approximately 1/10 of dislocation density of seed used to form the bulk crystal and wafers. Masks are formed selectively on GaN seed dislocations, and new GaN grown on the seed has fewer dislocations and often 1/10 or less of dislocations present in seed.

An apparatus for micromachining a semiconductor material from opposing sides through synchronous coordination of laser and electrochemistry includes an optical path system, a stable low-pressure jet generation system, and an electrolytic machining system. The optical path system includes a laser generator, a beam expander, a reflector, a galvanometer, and a lens. The electrolytic machining system includes a direct-current pulsed power supply, an adjustable cathode fixture, an electrolyte tank, a current probe, and an oscilloscope. The stable low-pressure jet generation system provides an electrolyte flow into a metal needle. The electrolyte flow forms an electrolyte layer between a semiconductor material and a cathode copper plate, such that the cathode and the anode are in electrical contact with each other. In a method employing the apparatus, a laser beam is irradiated onto the semiconductor material to form a local high-temperature region, which leads to a localized increase in electrical conductivity.

GaN wafers and bulk crystal have dislocation density approximately 1/10 of dislocation density of seed used to form the bulk crystal and wafers. Masks are formed selectively on GaN seed dislocations, and new GaN grown on the seed has fewer dislocations and often 1/10 or less of dislocations present in seed.