Quantitative Imaging of Defect Distributions in CdZnTe Wafers Using Combined Deep-Level Photothermal Spectroscopy, Photocarrier Radiometry, and Lock-In Carrierography

Trap-state kinetic parameters were investigated in CdZnTe wafers using nondestructive and noncontacting deep-level photothermal spectroscopy (DLPTS), heterodyne photocarrier radiometry (HePCR), and lock-in carrierography (HeLIC) imaging. Two electronic carrier traps were found and activation energies were measured. Using a two-trap frequency-domain rate-equation theoretical model, full-wafer quantitative HeLIC images of recombination times, capture and emission coefficients, trap densities, and emission/capture relaxation times were reconstructed at 100 K. HeLIC imaging was used to discuss dynamic photocarrier interactions with CdZnTe traps. These quantitative images are very important in determining the optoelectronic behavior and the quality of CdZnTe substrate materials and fabricated devices, which is controlled by complex free-carrier density wave (CDW) and defect configuration interaction kinetic processes.