Semiconductor device and method of manufacturing the same

A bipolar transistor comprising:

• a substrate having an insulating main surface;
• a semiconductor layer arranged on said main surface and having an end face which forms an angle with respect to said main surface;
• a side contact layer arranged on said end face;
• a first region of a first conductivity type which is formed in said semiconductor layer;
• a second region of a second conductivity type which is formed by diffusing a first impurity into said semiconductor layer through said end face from said side contact layer used as a solid-phase diffusion source of said first impurity, said second region contacting said first region, being unexposed to said end face, and having an impurity concentration which is substantially uniform in a direction parallel to said end face;
• a third region of the first conductivity type which is formed by diffusing second impurity into said semiconductor layer through said end face from said side contact layer used as a solid phase diffusion source of said second impurity, said third region being in contact with said second region, being exposed to said end face, and having an impurity concentration which is substantially uniform in a direction parallel to said end face;
• and
• first, second, and third electrodes respectively connected to said first and second regions, and to said third region through said side contact layer.