The present disclosure provides a method and system for fabricating a semiconductor device. The method and system of the present disclosure, after obtaining the polysilicon layer, first form the protective oxide layer on the surface of the polysilicon layer, and then etch the protective oxide layer and the protrusions on the surface of the polysilicon layer with the buffered oxide etchant based on controllability of the buffered oxide etchant, thereby reducing the protrusions on the surface of the polysilicon layer, while well protecting the surface of the polysilicon layer. Therefore, the technical problem of surface roughness in the existing polysilicon layers is solved.

The present disclosure provides a method and system for fabricating a semiconductor device. The method and system of the present disclosure, after obtaining the polysilicon layer, first form the protective oxide layer on the surface of the polysilicon layer, and then etch the protective oxide layer and the protrusions on the surface of the polysilicon layer with the buffered oxide etchant based on controllability of the buffered oxide etchant, thereby reducing the protrusions on the surface of the polysilicon layer, while well protecting the surface of the polysilicon layer. Therefore, the technical problem of surface roughness in the existing polysilicon layers is solved.

A SiC composite substrate includes a SiC single crystal layer and at least one biaxially oriented SiC layer. The at least one biaxially oriented SiC layer is disposed on the SiC single crystal. In the biaxially oriented SiC layer, the SiC is oriented in both a c-axis direction and an a-axis direction. The biaxially oriented SiC layer has pores and has a density of defect reaching the surface of 1.0×10.sup.1/cm.sup.2 or less.

The present invention discloses a multi-element perovskite material, and a single crystal, powder and a film thereof, as well as the applications thereof in photoluminescence and electroluminescence, in which the multi-element perovskite material is a multi-element fully-inorganic salt of non-lead metal halide and has a perovskite structure; and the chemical formula of the multi-element perovskite material is Cs.sub.2Na.sub.xAg.sub.1-xIn.sub.yBi.sub.1-yCl.sub.6, wherein 0≤x≤1, 0≤y≤1. Meanwhile, based on the very strong self-trapped exciton states of the double perovskite, the present invention proposes a high-efficiency single-phase broadband phosphor and an electroluminescent device.

A method for fabricating an ultra-thin graphite film on a silicon carbide substrate includes the steps of: (A) providing a polyamic acid solution and a siloxane-containing coupling agent for polymerizing under an inert gas atmosphere to form a siloxane-coupling-group-containing polyamic acid solution; (B) performing a curing process after applying the siloxane-coupling-group-containing polyamic acid solution to a silicon carbide substrate; (C) placing the silicon carbide substrate in a graphite crucible before placing the graphite crucible in a reaction furnace to perform a carbonization process under an inert gas atmosphere; (D) subjecting the silicon carbide substrate to a graphitization process to obtain a graphite film, thereby make it possible to fabricate an ultra-thin graphite film of high-quality on the surface of silicon carbide in a lower graphitization temperature range.

A method for fabricating an ultra-thin graphite film on a silicon carbide substrate includes the steps of: (A) providing a polyamic acid solution and a siloxane-containing coupling agent for polymerizing under an inert gas atmosphere to form a siloxane-coupling-group-containing polyamic acid solution; (B) performing a curing process after applying the siloxane-coupling-group-containing polyamic acid solution to a silicon carbide substrate; (C) placing the silicon carbide substrate in a graphite crucible before placing the graphite crucible in a reaction furnace to perform a carbonization process under an inert gas atmosphere; (D) subjecting the silicon carbide substrate to a graphitization process to obtain a graphite film, thereby make it possible to fabricate an ultra-thin graphite film of high-quality on the surface of silicon carbide in a lower graphitization temperature range.

Provided are a dielectric material, a device including the dielectric material, and a method of preparing the dielectric material, in which the dielectric material may include: a layered perovskite compound, wherein the layered perovskite compound may include at least one selected from a Dion-Jacobson phase, an Aurivillius phase, and a Ruddlesden-Popper phase, a temperature coefficient of capacitance (TCC) of a capacitance at 200° C. with respect to a capacitance at 40° C. may be in a range of about −15 percent (%) to about 15%, and a permittivity of the dielectric material may be 200 or greater in a range of about 1 kilohertz (kHz) to about 1 megahertz (MHz).

Forming a two-dimensional Janus layer includes forming a layer of MX.sub.2, where M is a transition metal and X is a first chalcogen, plasma etching the layer of MX.sub.2 to remove X from the top layer, thereby yielding an etched layer, and contacting the etched layer with a second chalcogen Y. The second chalcogen is different than the first chalcogen, resulting in a two-dimensional Janus layer including MXY.

An electro-optical waveguide modulator device includes a seed layer on a substrate, the seed layer having a first crystallographic plane aligned with a surface of the seed layer, an electro-optical channel extending in a first direction on the seed layer and having a second crystallographic plane aligned with the surface of the seed layer, an insulator layer on both sides of the electro-optical channel on the substrate in a second direction perpendicular to the first direction, an electrode barrier layer on the electro-optical channel and the insulator layer, and one or more of electrodes extending in the second direction. The seed layer and the insulator layer each comprise material having a refractive index that is lower than the electro-optical channel.

An electro-optical waveguide modulator device includes a seed layer on a substrate, the seed layer having a first crystallographic plane aligned with a surface of the seed layer, an electro-optical channel extending in a first direction on the seed layer and having a second crystallographic plane aligned with the surface of the seed layer, an insulator layer on both sides of the electro-optical channel on the substrate in a second direction perpendicular to the first direction, an electrode barrier layer on the electro-optical channel and the insulator layer, and one or more of electrodes extending in the second direction. The seed layer and the insulator layer each comprise material having a refractive index that is lower than the electro-optical channel.