  The frozen internal polarization-induced electric fields due to broken
inversion symmetry in all conventional blue and green nitride semiconductor
light emitting semiconductor quantum well heterostructures point in a direction
opposite to what is desired for efficient flow of electrons and holes. This
state of affairs has persisted because of the desire to have p-type hole
injectors on top of the quantum well active region. Because of the internal
polarization fields in nitride heterostructures, there exist four permutations
of doping and polarization for the realization of such light emitters. Which
permutation is the most desirable for efficient light emission? In this work,
we answer this question by demonstrating a fundamentally new approach towards
efficient light emission with bottom-tunnel junctions. The bottom-tunnel
junction design aligns the polarization fields in a desired direction in the
quantum well, while simultaneously eliminating the need for p-type contacts,
and allowing efficient current spreading. By preventing electron overshoot past
quantum wells, it disables carrier recombination in undesired regions of the
quantized heterostructures, and opens up the possibility for new geometries of
integrating and stacking multiple light emitters. Due to the inherent
advantages, the bottom-tunnel junction light emitting diode enables a 200-300%
increase in the light emission efficiency over alternate heterostructure
designs.
