Presentation Details
| Electrical Contact Behavior and Band Alignment at Metal/Cd-Se-Te Interfaces Mark Mills1, 2, Jing Shang1, 2, Magesh Murugesan1, John McCloy1, 2. 1Institute of Materials Research, Washington State University, Pullman, WA, USA.2School of Mechanical and Materials Engineering, Pullman, WA, USA |
Abstract
Accurate The influence of metal contacts on the electrical characterization of Cd-Se-Te (CST) materials was investigated using Hall-effect, current-voltage (I–V), and transmission line method (TLM) measurements. Hall measurements performed on the same p-type arsenic-doped CdSe0.15Te0.85 (p-CST) sample exhibited more than an order-of-magnitude variation in apparent carrier density depending on the contact metal, indicating significant contact-limited transport effects. To identify the origin of this behavior, Au, In and Ni contacts were evaluated under dark and ambient-light conditions. TLM analysis revealed substantial differences in contact resistance and carrier injection behavior among the investigated contacts. Au provided the most favorable hole contact for p-CST, whereas In provided the most favorable electron contact for n-type indium-doped CdSe0.4Te0.6 (n-CST). Comparison of experimentally extracted barrier heights with Schottky–Mott predictions showed substantially weaker work-function dependence than predicted by ideal Schottky–Mott theory, with barriers confined to ~0.62–0.79 eV for p-CST and ~0.27–0.38 eV for n-CST despite much larger predicted ranges of ~0.55–1.83 eV and ~0–0.90 eV, respectively. This reduced work-function sensitivity, together with the preservation of polarity-dependent contact behavior, is consistent with partial Fermi-level pinning at metal/CST interfaces. These results further indicate that contact performance in CST cannot be reliably predicted from work-function matching alone and highlight the importance of direct contact evaluation for reliable characterization and electrode selection in Cd-Se-Te photovoltaic materials.
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