A dielectric‐constant‐controlled tunnel junction for III‐nitride light‐emitting diodes

Abstract

Due to the low hole mobility and the unsatisfying p‐type doping efficiency, the p‐type layer has a low effective hole concentration and a large electrical resistivity that result in poor hole injection efficiency and significant current crowding effect for III‐nitride light‐emitting diodes (LEDs). In this work, we report a III‐nitride LED architecture comprising a dielectric‐constant‐controlled tunnel junction to improve both the current spreading effect and the hole injection efficiency. The dielectric‐constant‐controlled tunnel junction is an n+‐GaN/AlGaN/p+‐GaN heterojunction, in which the dielectric constant for the AlGaN layer is smaller than that for the GaN layer, and therefore, compared to the conventional n+‐GaN/p+‐GaN homojunction, the electric field within the tunnel junction is increased and hence, the hole injection can be substantially enhanced if the n+‐GaN/AlGaN/p+‐GaN heterojunction is properly designed. Furthermore, the proposed device can better spread the current compared to the LED without a tunnel junction. As a result, the internal quantum efficiency has been improved for the LED possessing the dielectric‐constant‐controlled tunnel junction.