A method of forming a monolithic LED precursor, the method comprising: (a) providing a substrate having a top surface; (b) forming a first semiconductor layer comprising a Group III-nitride on the top surface of the substrate; (c) selectively masking the first semiconductor layer with a LED mask layer, the LED mask layer comprising an aperture defining a LED well through a thickness of the LED mask layer to an unmasked portion of the first semiconductor layer, the LED well comprising LED well sidewalls extending from a top surface of the first semiconductor layer to a top surface of the LED mask layer; wherein a collimating portion of each LED well sidewall extending from the first semiconductor layer extends in a direction generally normal to the first semiconductor layer; and a tapered portion of each LED well sidewall extending between the collimating portion and the top surface of the LED mask layer is inclined such that a cross sectional area of the LED well in a plane parallel to the top surface of the first semiconductor layer decreases in the direction from the top surface of the first semiconductor layer towards the top surface of the LED mask layer, (d) selectively forming a monolithic LED stack within the LED well on the unmasked portion of the first semiconductor layer, the monolithic LED stack comprising: a n-type semiconductor layer comprising a Group III-nitride formed on the first semiconductor layer; an active layer formed on the n-type semiconductor layer comprising one or more quantum well sub-layers, the active layer comprising a Group III-nitride; a p-type semiconductor layer comprising a Group III-nitride formed on the active layer; wherein LED stack sidewalls of the monolithic LED stack extending from the top surface of the first semiconductor layer conform to the LED well sidewalls of the LED mask layer. (a) providing a substrate having a top surface; (b) forming a first semiconductor layer comprising a Group III-nitride on the top surface of the substrate; (c) selectively masking the first semiconductor layer with a LED mask layer, the LED mask layer comprising an aperture defining a LED well through a thickness of the LED mask layer to an unmasked portion of the first semiconductor layer, the LED well comprising LED well sidewalls extending from a top surface of the first semiconductor layer to a top surface of the LED mask layer; wherein a collimating portion of each LED well sidewall extending from the first semiconductor layer extends in a direction generally normal to the first semiconductor layer; and a tapered portion of each LED well sidewall extending between the collimating portion and the top surface of the LED mask layer is inclined such that a cross sectional area of the LED well in a plane parallel to the top surface of the first semiconductor layer decreases in the direction from the top surface of the first semiconductor layer towards the top surface of the LED mask layer, (d) selectively forming a monolithic LED stack within the LED well on the unmasked portion of the first semiconductor layer, the monolithic LED stack comprising: a n-type semiconductor layer comprising a Group III-nitride formed on the first semiconductor layer; an active layer formed on the n-type semiconductor layer comprising one or more quantum well sub-layers, the active layer comprising a Group III-nitride; a p-type semiconductor layer comprising a Group III-nitride formed on the active layer; a n-type semiconductor layer comprising a Group III-nitride formed on the first semiconductor layer; an active layer formed on the n-type semiconductor layer comprising one or more quantum well sub-layers, the active layer comprising a Group III-nitride; a p-type semiconductor layer comprising a Group III-nitride formed on the active layer;