APPLICATION OF URBACH-RULE OPTICAL-ABSORPTION TO COMPOSITION MEASUREMENT OF CD1-YZNYTE

The optical absorption coefficient of Cd1-yZnyTe near the fundamental band edge was measured at room temperature using transmission spectros copy. Like in other II-VI semiconductors, it was found that the absorp tion coefficient exhibits an exponential dependence on incident photon energy according to Urbach's rule. It was also found that the exponen tial parameters depend on composition, y, of Cd1-yZnyTe. A technique i s described for determining the composition of Cd1-yZnyTe from optical transmission spectroscopy. This technique has been implemented in the manufacturing of Cd1-yZnyTe substrates for lattice matched epitaxial growth of HgCdTe.