A simple way to analyze infrared reflectivity spectra of p-type Hg0.78Cd0.22Te implanted in various conditions

Different ion-implanted p-type Hg0.78Cd0.22Te samples were analyzed by infr ared reflectivity in the 2-20 mu m wavelength range. We show how to derive some characteristic values of the free carriers induced by ion implantation from simple models of the implanted samples. For low energy implantations (Al (320 keV)) an excess of electrons with concentration n(+) approximate t o 5x10(17) cm(-3) for doses 10(12) and 10(14) ions cm(-2) is observed betwe en the surface and the projected range R-p of the ions, in agreement with t he well-known change of type of the free carriers induced by the ion implan tation in this kind of samples. High energy alpha particle (0.8 and 2 MeV, 10(14) ions cm(-2)) implantations lead to a pronounced inhomogeneous concen tration of free electrons with n(+) approximate to 9.2 x 10(16) cm(-3) betw een the surface and R-p where a negligible amount of defects due to the nuc lear energy loss is formed, and n(+)approximate to 1.6x10(17) cm(-3) betwee n R-p and R-p+Delta R-p, Delta R-p being the longitudinal straggling, where the defect production rate through the nuclear energy loss mechanism is ma ximum. (C) 1999 Elsevier Science B.V. All rights reserved.