Emitter passivation by charge injection

We have discovered a new means for engineering of emitter recombination and saturation current, J₀, using corona controlled charge injection to deep dielectric traps near the interfacial region. The injected charge remains at the interface after removal of the corona charge from the dielectric surface, creating a highly desired low emitter recombination state. The effect is demonstrated for p⁺ emitters on n-substrates, passivated with a SiO₂/SiN_x stack. The desired charge injection is created by positive corona charging that causes electron tunneling through the interfacial SiO₂ film to traps in the SiN_x. It should be noted that passivation by injection requires opposite corona polarity to that used in past field-effect passivation studies. The new phenomenon may be of importance, not only for fundamental understanding, but conceivably, also as a means of controlling the charge in the next generation of advanced cells employing dielectric stacks for emitter passivation.