Relaxation dynamics inside HgCdTe/CdZnTe IR photodiodes and avalanche detectors

Due to its bandgap tunability over the infrared spectrum, HgCdTe/CdZnTe is used to cover most IR detection applications, but performance depends on the density of dislocations so that lattice matching of epitaxial HgCdTe is targeted. Theoretically possible with a proper choice of Zn fraction, it is practically impossible to achieve over large areas. Thus, mismatch induced strain must be carefully evaluated and its consequences for dislocation generation anticipated. Here we propose to use a microLaue diffraction to access in depth strain profiling of HgCdTe/CdZnTe single layer samples with different strain ranging from compressive to tensile. The experiment will be coupled to a flexion setup for additional quantitative information upon the kinetics of plastification in this material system. Finally, a multilayer avalanche photodiode structure with complex strain distribution will be measured to validate the single layer results and emphasize their implication on real device stacks