Blue to yellow emission from (Ga,In)/GaN quantum wells grown on pixelated silicon substrate

It is shown that substrate pixelisation before epitaxial growth can significantly impact the emission color of semiconductor heterostructures. The wavelength emission from In_xGa_1-xN/GaN quantum wells can be shifted from blue to yellow simply by reducing the mesa size from 90 × 90 µm² to 10 × 10 µm² of the patterned silicon used as the substrate. This color shift is mainly attributed to an increase of the quantum well thickness when the mesa size decreases. The color is also affected, in a lesser extent, by the trench width between the mesas. Cathodoluminescence hyperspectral imaging is used to map the wavelength emission of the In_xGa_1-xN/GaN quantum wells. Whatever the mesa size is, the wavelength emission is red-shifted at the mesa edges due to a larger quantum well thickness and In composition.