Performance Enhancement of Microwave GaN HEMTs Without an AlN-Exclusion Layer Using an Optimized AlGaN/GaN Interface Growth Process
| Autor: | Mattias Thorsell, Sebastian Gustafsson, Anna Malmros, Niklas Rorsman, Erik Janzén, Jr-Tai Chen, Johan Bergsten, Urban Forsberg |
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| Rok vydání: | 2016 |
| Předmět: |
010302 applied physics
Electron mobility Materials science business.industry Scattering Transistor Wide-bandgap semiconductor 02 engineering and technology Surface finish Chemical vapor deposition 021001 nanoscience & nanotechnology 01 natural sciences Electronic Optical and Magnetic Materials law.invention law 0103 physical sciences Parasitic element Optoelectronics Electrical and Electronic Engineering 0210 nano-technology business Microwave |
| Zdroj: | IEEE Transactions on Electron Devices. 63:333-338 |
| ISSN: | 1557-9646 0018-9383 |
| DOI: | 10.1109/ted.2015.2501838 |
| Popis: | The impact of the sharpness of the AlGaN/GaN interface in high-electron mobility transistors (HEMTs) is investigated. Two structures, one with an optimized AlGaN/GaN interface and another with an unoptimized, were grown using hot-wall metal-organic chemical vapor deposition. The structure with optimized sharpness of the interface shows electron mobility of 1760 cm2/V $\cdot $ s as compared with 1660 cm2/V $\cdot $ s for the nonoptimized interface. Gated Hall measurements indicate that the sharper interface maintains higher mobility when the electrons are close to the interface compared with the nonoptimized structure, indicating less scattering due to alloy disorder and interface roughness. HEMTs were processed and evaluated. The higher mobility manifests as lower parasitic resistance yielding a better dc and high-frequency performance. A small-signal equivalent model is extracted. The results indicate a lower electron penetration into the buffer in the optimized sample. Pulsed- IV measurements imply that the sharper interface provides less dispersive effects at large drain biases. We speculate that the mobility enhancement seen AlGaN/AlN/GaN structures compared with the AlGaN/GaN case is not only related to the larger conduction band offset but also due to a more well-defined interface minimizing scattering due to alloy disorder and interface roughness. |
| Databáze: | OpenAIRE |
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