Composition and thickness control of thin LPE HgCdTe layers using X-ray diffraction

Double-axis x-ray rocking curve measurements have been used to nondestructi vely characterize the composition profile of HgCdTe heterojunction photodio de structures grown by liquid phase epitaxy (LPE). In particular, the thick ness and composition profile of the thin graded-composition cap layer are d etermined through an empirical correlation between rocking curve parameters and composition profiles measured by SIMS. Spatial maps of cap layer thick ness and composition are generated from automated measurements of x-ray roc king curves across a wafer. X-ray mapping has been instrumental in improvin g the spatial uniformity of cap layers and in maintaining control of the gr owth process in Hg-rich LPE dipping reactors.