Prof. Böer at the Institute of Energy Conversion this spring
March 12, 2015 - Karl W. Böer, distinguished professor of physics and solar energy, gave a presentation at the Institute of Energy Conversion titled "How to turn CdS p-type using hyper-high-field Böer Domains." He showed that at 125 kV/cm gold electrodes can inject massively holes into CdS, inverting it to become p-type, turning the well-known quenching spectrum with electron density minima at 0.9, 1.2 and 1.3 μm into maxima at nearly the same wavelength. He also showed that a 200Å thick layer of CdS on top of a CdTe solar cell prevents junction leakage and causes its open circuit voltage to attain its theoretical limit of the CdTe band gap at 1.45 eV. The junction is now shifted into the CdS and the Conduction band edges are separated by 0.4eV with a concurrent shift of the electron affinity. Karl Böer has also received his latest book, published by Springer, The Handbook of Thin-Film Solar Cells. He is currently writing the third edition of the Handbook on Semiconductor Physics with Professor Udo Pohl, TU Berlin. The first 12 chapters are available as electronic versions from Springer. In the last year he has published four papers: a featured article in the Annalen der Physik on "High-Field Domains that remain attached to the Electrodes in CdS"; in Physical Review, "Two high-field thermodynamically stable conductivity states in photoconducting CdS, one n-type and one p-type"; in physica status solidi, "Stationary Anode-adjacent Hyper-High-Field Böer Domains to render an entire CdS Crystal p-type by massive Hole Injection"; and in J. Solar Cells, "Hyper-High-Field Domains in CdS Cover Layers may prevent Junction Leakage through Thin-Film Heterojunction Solar Cells."