1. A method of forming a punch-through diode comprising: forming a first semiconductor region of a first conductivity type and having a first peak impurity concentration; forming a second semiconductor region adjacent to the first semiconductor region and having a second peak impurity concentration that is less than the first peak impurity concentration; forming a third semiconductor region of a second conductivity type adjacent to the second semiconductor region and having a third peak impurity concentration that is greater than the second peak impurity concentration; forming a fourth semiconductor region adjacent to the third semiconductor region and having a fourth peak impurity concentration that is less than the third peak impurity concentration; and forming a fifth semiconductor region of the first conductivity type adjacent to the fourth semiconductor region and having a fifth peak impurity concentration that is greater than the peak third impurity concentration.