Optical evaluation of indium gallium arsenide phosphide double-heterostructure material for injection lasers

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Abstract
Optical methods used for evaluation of InGaAsP double‐heterostructure (DH) material are described. The photoluminescence (PL) efficiency of the active layer in DH wafers and its spatial variation are shown to be correlated with the threshold current density of the broad area lasers processed from the corresponding wafers. The simultaneous measurement of the PL signal and the transmitted intensity of the excitation source through the active layer is a useful technique for monitoring imperfection in the active layer. The sheet conductivity of the epitaxial p layers and p‐n junction misplacement can be determined from the variation of the PL signal as a function of the power of the optical pump source. In addition, conventional spectrally and spatially resolved PL indicates the compositional homogeneity and the doping concentration of the active layer. In general, we find the 1.06‐μm yttrium aluminum garnet (YAG) laser to be a most convenient tool for evaluation of InGaAsP DH material.