Monochromatic emitters on coalesced selective area growth nanocolumns

A method of fabricating light emitting structure comprising an array of negatively-doped or positively-doped GaN nanocolumns having a coalesced substrate, the nanocolumns being grown using molecular beam epitaxy at a low temperature such that the coalesced substrate has an enhanced compatibility with a multiple quantum well structure, multiple quantum wells formed on the coalesced substrate by molecular beam epitaxy by including indium (In), and a layer of positively-doped or negatively-doped GaN formed on the multiple quantum wells using molecular beam epitaxy, the method comprising:

• providing a growth substrate with a mask defining apertures for the nanocolumns;
• heating the growth substrate to a first temperature of about 785° C. suitable for reducing defects in the multiple quantum wells formed on said coalesced substrate and;
• controlling a flux of nitrogen with respect to gallium to grow in the apertures at the first temperature the negatively-doped or positively-doped GaN nanocolumns using molecular beam epitaxy while preventing material from growing on the mask between the apertures until the coalesced substrate is formed;
• heating the growth substrate and said coalesced substrate to a second temperature of about 650° C. or less suitable for forming the multiple quantum wells with at least indium having an enhanced compatibility with said coalesced substrate;
• controlling a flux of the indium to form barrier layers of GaN and at least one active layer of InGaN to provide the multiple quantum wells on the coalesced substrate using molecular beam epitaxy;
• and
• heating the growth substrate and said coalesced substrate to a third temperature of about 760 to about 785° C.;
• and
• forming an upper layer of the positively-doped or negatively-doped GaN on the multiple quantum wells (MQWs).