significance of gate current for SCR !!!

when the gate current is applied at the gate terminal of SCR ,a significant number of electrons from n2 layer cross the junction J3. It is because N2 layer is heavily doped as compared to p2 layer.after crossing the junction j3 ,these electrons diffuse through p2 layer .the electrons are then swept across junction j2 into the n1 layer .These electrons in n1 layer reduce the positive space charge on the n1 side of depletion layer .
this leads to reduction of the width of depletion layer around the junction j2.
resuslts ..SCR tunrs ON..