Direct imaging of minority charge carrier transport in luminescent semiconductors
Luber, David R.
Haegel, Nancy M.
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A quantitative method for extracting minority carrier diffusion and drift lengths is developed and demonstrated in a heavily-doped semiconductor heterostructure. This method advances the high resolution transport imaging technique, yielding key material parameters with a single, non-destructive measurement. This is the first demonstration of an SEM-based, contact-free, non-destructive technique for high-resolution minority carrier lifetime measurement. The measured values are in excellent agreement with theoretical calculations. The imaging transport technique is also employed to image the nature of the generation region as a function of beam energy, probe current and sample atomic number. These types of images should be useful to allow for experimental verification of resolution limits in CL and EBIC associated with interaction volume effects in bulk materials and can be obtained without additional sample preparation. Finally, several suggestions for further research are offered, including mapping of radiation damage in solar cells, near-contact E field mapping and studies of low-dimensional structures such as superlattices and quantum wires. These nanoscale structures are poised to usher-in the next revolution in solid-state electronic devices.