Control of yellow photoluminescence in AlGaN/GaN heterostructures

Photoluminescence with the peak corresponding to yellow color of the visible spectrum (so-called yellow luminescence) originates from deep levels in the GaN buffer layers of heterostructures and depends on heterostructure growth conditions. In turn deep levels affect the resistance of Ohmic contacts of microwave transistors fabricated from these heterostructures. This determines the reliability of GaN microwave transistor operation.

Two types of units for control of photoluminescence with the peak in the yellow visible spectral region have been designed with the aim to control the quality of AlGaN/GaN/SiC and AlGaN/GaN/Al₂O₃ heterostructures. One of the units is used for fast control of yellow photoluminescence and the other for photoluminescence mapping on heterostructure wafer surfaces. Examples of photoluminescence maps for structures grown on different substrates have been given.