FULL BAND-STRUCTURE CALCULATION OF MINORITY-CARRIER LIFETIMES IN HGCDTE AND THALLIUM-BASED ALLOYS

We have calculated the full, band structures-based-minority carrier li fetimes in small-gap semiconductor alloys. The contribution from first -order Coulomb interactions and second-order electron-electron interac tions coupled through optical phonons are included. Our results agree reasonably well with experiments in Hg0.78Cd0.22Te. Similar calculatio ns were carried out for lifetimes in In0.85Tl0.15As, and In0.92Tl0.08S b. The minority carrier lifetimes in In0.67Tl0.33P and In0.92Tl0.08 Sb are shorter than that in Hg0.78Cd0.22Te at all temperatures. However, the low-temperature minority carrier lifetime in In0.85Tl0.15As is an order of magnitude longer than that in Hg0.78Cd0.22Te. Our calculatio ns further suggest the possibility of increasing the lifetimes of mino rity carriers either by decreasing the density of states inside a crit ical energy and momentum region or by increasing the total hole popula tion outside that critical region. Experimental observations that subs tantiate this suggestion are discussed.