Effect of GaN substrate thickness on the optical field of InGaN lasers diodes

In this work the influence of GaN substrate thickness on the near and far-field patternsof InGaN lasers structures is analyzed. In simulation a conventional separateconfinement heterostructure of InGaN-MQW / GaN / AlGaN is considered. Afluctuating behavior is found, showing that for some values of the substrate thicknessthe near and far- field patterns can be optimized and there are critical values of thesubstrate thickness that produce the lowest values of the confinement factor and thehigher values of the full wide half-maximum of the far field. It is also shown that bysubstituting the GaN contact layer by an AlxGa1-xN layer with a parabolic variation ofthe Al content it is possible to reduce the optical field leakage to substrate. Resultsindicated that properly choosing the thickness of the substrate and replacing the n-GaNcontact layer by a graded-index (GRIN) AlxGa1-xN layer it is possible to improve boththe confinement factor and Far field pattern in nitride lasers.