THE SPATIAL-DISTRIBUTION OF LIGHT FROM SILICON LEDS

Well-defined light patterns emitted from circular guard ring avalanche silicon photodiodes made on CZ substrates provide an experimental pro of that the reverse current does not flow all over the junction area. This fact should be taken into account in calculations of current dens ities in future device design considerations. The light patterns origi nate from zones of crystal striations. These striations, which are usu ally considered to be a negative factor, are utilized here to control the overall light-emission intensity. It is shown that the light-patte rn dimensions and intensity are current controlled. The percentage of light area coverage, the overall emitted light intensity and the avera ge reverse-current density are interrelated and determined as a functi on of the operating current. Four distinct regions of operation are id entified. It is shown that the emitted light intensity is directly pro portional to the area of light emission in three of the regions (low, medium and high currents) even at high junction temperatures. The resu lts are application oriented with regard to the design of future silic on light-emitting diodes (LEDs).