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).