New approach towards efficient light emission with bottom-tunnel junctions is developed. The bottom-tunnel junction design aligns the polarization fields in a desired direction in the vicinity of 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 heterostructures, increasing injection efficiency and opening new possibilities in heterostructure design. InGaN-based buried-tunnel junction is used to construct first monolithically grown p-type-down laser diode on n-type, Ga-polar bulk GaN substrate. Unique advantages of such construction that enables to separate design of carrier injection and optical mode confinement for such laser diode structures is discussed.