Electroluminescence from Gunn domains in GaAs MESFETS as a means for defect detection

The emission of visible light from the high-field region near the drain of GaAs/AlGaAs MESFETs has been used to study the quality of fabricated transistors. Inhomogeneities or bright spots in the emission have proven to indicate the presence of defects in the gate/drain spacing or surface contaminants, such as re-deposited gate material. Processing abnormalities of 0.5 mym diameter are easily seen. The time-variation of emission from the brightest spots is characteristic of the formation of microplasmas the location of which will often predict the site of destructive device breakdown.