A semiconductor device is presented, which includes a semiconductor substrate with a high concentration impurity of a first type conductivity and an epitaxial layer with a low concentration impurity provided on the semiconductor substrate, where a trench coupled to the semiconductor substrate is provided...http://www.google.com/patents/US7968970?utm_source=gb-gplus-sharePatent US7968970 - Semiconductor device, method for manufacturing semiconductor device, and power amplifier element
