A LATERAL INJECTION POROUS SILICON DEVICE STRUCTURE FOR LIGHT-EMITTING-DIODES

Lateral injection porous silicon (PS) diodes and metal-pg-metal(MPM) structures incorporated with PS-on-oxide structures are fabricated and characterized. The porous Si and the bottom oxide are formed in the same electrochemical cell but with different chemical solutions. The bottom oxide provides good isolation for the current flowing in the PS region and the current density level is higher compared with the counterpart without bottom oxide. Strong red-orange photoluminescence is observed under daylight, but the electroluminescence is weak owing to the lack of efficient hole injectors and the too thick gold contact films of the samples. A charging effect during electrical measurements and a punch-through-like behaviour at higher voltages are observed in the characteristics of MPM samples, suggesting a large number of traps and the ease of depletion in PS. The diode with bottom oxide is well behaved except for the large series resistance. The PS-on-oxide technique is shown to be beneficial for lateral porous Si devices.