A polysilicon based bipolar-like avalanche light-emitting diode with an enhanced avalanche breakdown effect

Abstract

The advantage of silicon-based avalanche N + P junction LEDs is that they are compatible with silicon CMOS processes and facilitate optoelectronic integration, but their relatively high operating voltage limits their applications. In view of this, we propose a polysilicon avalanche LED (light-emitting device) with a bipolar-like structure that has a different avalanche breakdown mechanism from that of a normal PN junction, achieving an operating voltage significantly lower than that of a conventional N + P LED. Five polysilicon avalanche LEDs with base lengths ranging from 4 µm to 10 µm have been fabricated and tested. They have proven to operate at voltages as low as about 6–7 V, while the conventional N + P LEDs used for comparison cannot operate below 9 V. We also observed that they have higher luminous efficiency than the conventional N + P LED. The luminous intensity of the bipolar-like LED with a base length of 4 μm is about 41 % higher than that of the conventional N + P LED at a power consumption of 0.4 W. This demonstrates the advantages of bipolar avalanche LEDs in all-silicon monolithic optoelectronic integration applications.