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

Abstract

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 rateequation 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.

Analytical model of the modulated photoluminescence in semiconductor materials

“…A newly developed method in MPL techniques is based on the simultaneous use of two modulating frequencies, to make heterodyne detection and observe non-linearities in high injection rate. In [11] and [12], the authors develop some analytical model to be able to interpret the results by computing the different parameters of the recombination paths. In our experiment and analysis, we use only one excitation frequency and a large modulation depth (more than 50%) and frequencies up to 100 MHz.…”