SEMICONDUCTOR DEVICE HAVING AMPLIFICATION FACTOR WITH LESS DEPENDENCE ON CURRENT VALUE

摘要

An object of the present invention is to amplify the current which varies by a factor of several orders of magnitude with a constant gain without using a complicated circuit. In order to solve the problem, with a semiconductor device includes a first semiconductor region of a first conductivity, a second semiconductor region which is an opposite conductivity and is in contact with the first semiconductor region and a third semiconductor region which is the first conductivity and is in contact with the second semiconductor region at the second surface, a fourth semiconductor region in contact with the second semiconductor region is provided so as to be separated from the third semiconductor region and enclose the third semiconductor region and an impurity concentration of the fourth semiconductor region is larger than that of the second semiconductor region.