Nitride light-emitting diodes for cryogenic temperatures

Abstract

A novel approach to fabricate efficient nitride light-emitting diodes (LEDs) grown on gallium polar surface operating at cryogenic temperatures is presented. We investigate and compare LEDs with standard construction with structures where p-n junction field is inverted through the use of bottom tunnel junction (BTJ). BTJ LEDs show improved turn on voltage, reduced parasitic recombination and increased quantum efficiency at cryogenic temperatures. This is achieved by moving to low resistivity n-type contacts and nitrogen polar-like built-in field with respect to current flow. It inhibits the electron overflow past quantum wells and improves hole injection even at T=12K. Therefore, as cryogenic light sources, BTJ LEDs offer significantly enhanced performance over standard LEDs.