Effect of photocarrier spreading on the photoluminescence of double heterostructure material

Lateral spreading of photoexcited carriers can suppress the photoluminescence signal from double heterostructure wafers containing a p-n junction independently from saturable defects in the material. Experimental results are presented and a theory is derived to show that in any double heterostructure with a p-n junction the photoluminescence is suppressed if the power of the excitation source does not exceed a threshold value. The threshold power has been calculated in terms of material parameters, in excellent agreement with experimental results. This effect is the basis of a novel technique used for a nondestructive optical determination of the p-clad layer sheet conductance as well as junction misplacement in double heterostructures, both of which are important parameters for injection lasers.