| AVS 63rd International Symposium & Exhibition | |
| Electronic Materials and Photonics | Monday Sessions |
| Session EM-MoA |
| Session: | Surface and Interface Challenges in Wide Bandgap Materials |
| Presenter: | Burcu Ozden, Auburn University |
| Authors: | B. Ozden, Auburn University M.P. Khanal, Auburn University C. Yang, Auburn University L. Shen, Auburn University V. Mirkhani, Auburn University K. Yapabandara, Auburn University M. Park, Auburn University |
| Correspondent: | Click to Email |
The nature and distributions of the electrically-active sub-bandgap point defects in the heterostructures of the AlGaN/GaN high electron mobility transistors (HEMTs) layers have been analyzed by using spectroscopic photo current voltage (SPIV) measurement. Despite the great potential, device performance for the next generation of high power electronics is often limited by the presence of electronic traps in the AlGaN/GaN HEMTs device structures. Therefore, the knowledge of defect distribution is critical in understanding the origin of the surface traps for mitigation in future device applications.
In this work, the AlGaN/GaN HEMT epi-layers were grown on a 6″ Si wafer by metal-organic chemical vapor deposition (MOCVD). Ni contacts with 600μm diameter and 20nm thickness were fabricated on the samples which are chosen from the three different locations of 6″ wafer. The SPIV measurement was performed using a variable-wavelength light illumination from a Xe lamp. Vertical bias was applied between circular semi-transparent Ni Schottky contacts and the bottom ohmic contact.
Presence of sub-bandgap defects at different energy levels among the wafer were revealed by SPIV measurements indicating nonhomogeneous defect distribution among the wafer. It was concluded that observed defects are most probably due to either Ga vacancies in GaN or Al vacancies in AlGaN by comparing the energy level of the defects with the formation energies of these vacancies. In conclusion, we have demonstrated the wafer quality in terms of the distribution of electrically active defects can be successfully assess by using SPIV measurements which will be useful for AlGaN/GaN HEMT wafer vendors as a diagnostic tool.