N+/p+ GaN and n+/p+ Al0.10Ga0.90N tunnel junctions: a promising alternative for hole injection in deep ultraviolet light-emitting diodes

Abstract

This research replaced the traditional hole source layers in a conventional LED with a tunnel junction. In conventional light-emitting diodes (LEDs) two hole injecting layers (p-GaN and p-AlxGa1-xN) have been used, in which holes have to surpass greater energy barriers that hindered holes injection. A heavily doped GaN tunnel junction (TJ) has been used as a replacement for conventionally used hole injection layers, which has reduced the energy barriers for holes and increased the electron confining ability of wells. As a result, the internal quantum efficiency (IQE) of the LED has increased from 52% to 72%. Instead of GaN TJ, Al0.10Ga0.90N – GaN hybrid tunnel junction (HTJ) has been introduced to lower the efficiency droop and raise the efficiency further to 81% simultaneously. Using TJ and HTJ, we have demonstrated that the conventional hole’s source layer can be replaced by TJs, which results in better hole injection because of reduced barrier height, increased electron confinement, greater electron–hole radiative recombination, and higher spontaneous emission intensity.