High-resolution x-ray and transmission electron microscopic analysis of a GaInAsSb AlGaAsSb multiple quantum well laser structure

High-resolution x-ray diffractometry (HRXRD) and transmission electron micr oscopy (TEM) are employed to characterize a quaternary IIIxIII1-xVyV1-y AlG aAsSb/GaInAsSb multiple quantum well (MQW) heterostructure. A method for un iquely determining the chemical composition of the strained quaternary quan tum well, information previously thought to be unattainable using HRXRD, is thoroughly described. The misconception that HRXRD can separately find the well and barrier thickness of a MQW from the pendellosung fringe spacing i s corrected and, thus, the need for TEM is motivated. Computer simulations show that the key in finding the well composition is the intensity of the h igher order satellite peaks in the diffraction pattern. For the AlGaAsSb/In GaAsSb MQWs analyzed in this work, the variation in the intensity of the th ird-order satellite peak is identified as a sensitive measure of the quantu m well composition. Using HRXRD on an MQW semiconductor laser device layer, the ability to resolve this higher order peak and interpret the informatio n contained in it is demonstrated for the first time. (C) 1999 American Ins titute of Physics. [S0021-8979(99)04311-X].