Semiconductor device, substrate, method for manufacturing semiconductor device, and method for manufacturing substrate

A semiconductor device, comprising:

• a first semiconductor region including a first compound including silicon and carbon;
• and
• a second semiconductor region including a second compound including silicon and carbon,
• the first semiconductor region including first to fourth regions,
• the first to third regions being positioned between the fourth region and the second semiconductor region,
• the second region being separated from the first region in a direction crossing a direction from the fourth region toward the second semiconductor region,
• the third region being positioned between the first region and the second region,
• the first region and the second region including germanium,
• the third region not including germanium, or a third peak concentration of germanium in the third region being lower than a first peak concentration of germanium in the first region and lower than a second peak concentration of germanium in the second region,
• the fourth region not including germanium, or a fourth peak concentration of germanium in the fourth region being lower than the first peak concentration and lower than the second peak concentration,
• a concentration of germanium in a portion of the second semiconductor region being 1/10 of the first peak concentration or more.

A substrate, comprising:

• a first semiconductor region including a first compound including silicon and carbon;
• and
• a second semiconductor region including a second compound including silicon and carbon,
• the first semiconductor region including first to third regions contacting the second semiconductor region,
• the third region being positioned between the first region and the second region,
• the first region and the second region including germanium,
• the third region not including germanium, or a concentration of germanium in the third region being lower than a concentration of germanium in the first region and lower than a concentration of germanium in the second region.

A substrate, comprising:

• a first semiconductor region including a first compound including silicon and carbon;
• and
• a second semiconductor region including a second compound including silicon and carbon,
• the first semiconductor region including first to fourth regions,
• the first to third regions being positioned between the fourth region and the second semiconductor region,
• the second region being separated from the first region in a direction crossing a direction from the fourth region toward the second semiconductor region,
• the third region being positioned between the first region and the second region,
• the first region and the second region including germanium,
• the third region not including germanium, or a third peak concentration of germanium in the third region being lower than a first peak concentration of germanium in the first region and lower than a second peak concentration of germanium in the second region,
• the fourth region not including germanium, or a fourth peak concentration of germanium in the fourth region being lower than the first peak concentration and lower than the second peak concentration,
• a concentration of germanium in a portion of the second semiconductor region being 1/10 of the first peak concentration or more.