Semiconductor device and method for manufacturing the same

A method for manufacturing a semiconductor device comprising:

• forming a first layer on an n-type semiconductor layer, the first layer being a metal layer including first atoms capable of being n-type impurities in the n-type semiconductor layer;
• forming a second layer on the first layer, the second layer being a metal layer including second atoms capable of being p-type impurities in the n-type semiconductor layer;
• forming a third layer on the second layer, the third layer being a metal layer including titanium atoms;
• forming a fourth layer on the third layer, the fourth layer being made of a metal material different from the metal material of the third layer;
• and
• heat-treating a stacked structure including the first to fourth layers.