Laser beam induced current studies of Hg1-xCdxTe photodiodes
Date of Award
School of Engineering and Mathematics
Faculty of Computing, Health and Science
Lnser-beam-induced-current (LBIC) is being investigated as a combined electrooptical (EO) alternative to individual electrical and optical based measurements of p-n junction photodiodes. The technique is non-destructive and employs a focused low-power laser beam that is scanned across the semiconductor surface, between two shortened ohmic contacts located at remote positions on either side of the scanned area. The LBIC image is then a two-dimensional map of the steady-state current-flow as a function of laser position. However, despite its simplicity, its application has thus far heen limited to either examining photodiodes in a qualitative manner, or, as mathematical analogy. This problem is largely due to the complexity of the physical process, and the difficulty in isolating the multitude of semiconductor material and device parameters that influcncc the LBIC profile. This work significantly develops the physical theory, and quantitative application of LBIC for the characterization of photodiodcs. Numerical modeling of the LBIC problem using thc full drift-diffusion and treatment of an n+ -on-p diode together with supporting experimental measurements have revealed a wealth of hidden physical mechanisms, quantifiable relationships, and conditions with which to characterize the p-n junction. A further revision to Nui's theoretical model for the lateral photovoltaic effect (LPE) has also been developed such that bulk recombination, surface recombination and junction leakage are taken into consideration. A study of the J orward problem
Gluszak, Edward A., "Laser beam induced current studies of Hg1-xCdxTe photodiodes" (2006). Theses: Doctorates and Masters. Paper 353.