Semiconductor device

A semiconductor device comprising:

• a substrate comprising a first surface and a second surface, wherein the first surface is on an opposite side of the substrate from the second surface ;
• an epitaxial layer on the first surface of the substrate, the epitaxial layer comprising a gate trench, wherein the epitaxial layer has a first conductivity type;
• a well region on the epitaxial layer and having a second conductivity type different from the first conductivity type;
• a channel layer having the first conductivity type on an inner sidewall of the gate trench, wherein the channel layer has a lower defect rate than that of the epitaxial layer;
• a gate electrode within the gate trench, wherein the gate electrode extends in a first direction;
• a gate insulating layer between the channel layer and the gate electrode;
• a source electrode on the well region;
• and
• a drain electrode on the second surface of the substrate,
• wherein the channel layer extends in the first direction and protrudes from a lower surface of the well region toward the first surface of the substrate.

A semiconductor device comprising:

• a substrate comprising a first surface and a second surface, wherein the first surface is on an opposite side of the substrate from the second surface;
• an epitaxial layer on the first surface of the substrate, the epitaxial layer comprising a gate trench, wherein the epitaxial layer comprises 4H-SiC;
• a channel layer comprising 3C-SiC, wherein the channel layer is on an inner sidewall of the gate trench and wherein the channel layer has a lower defect rate than that of the epitaxial layer;
• a gate electrode in the gate trench;
• a gate insulating layer between the channel layer and the gate electrode;
• a source electrode on the epitaxial layer;
• and
• a drain electrode on the second surface of the substrate.