- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
High germanium doping of GaN films by ammonia molecular beam epitaxy
摘要： Doping Gallium nitride (GaN) with elemental Germanium (Ge) grown by ammonia molecular beam epitaxy is presented. Growth studies varying the GaN growth rate, substrate growth temperature and the elemental Ge flux reveal several incorporation dependencies. Ge incorporation increases with flux, as expected, and a doping range from ~1017 cm-3 to 1020 cm-3 was readily achieved. A strong substrate temperature dependence on the electrical properties of films grown is observed, with an optimal growth temperature of 740 °C, lower than standard GaN growth conditions for the ammonia molecular beam epitaxy. Compensation effects at higher growth temperatures are suspected, as observed with other techniques. Crystallographic defects are apparent at the highest doping concentrations from electrical and optical measurements, however thin layers of such highly doped films are of great interest for contact layers and tunnel junctions in devices.
关键词： Ammonia Molecular Beam Epitaxy,Molecular Beam Epitaxy,Tunnel Junctions,Germanium Doping,Gallium Nitride
更新于2025-09-04 15:30:14
-
Analysis of gaseous ammonia (NH3) absorption in the visible spectrum of Jupiter - Update
摘要： An analysis of currently available ammonia (NH3) visible-to-near-infrared gas absorption data was recently undertaken by Irwin et al. (Icarus, 302 (2018) 426) to help interpret Very Large Telescope (VLT) MUSE observations of Jupiter from 0.48–0.93 μm, made in support of the NASA/Juno mission. Since this analysis a newly revised set of ammonia line data, covering the previously poorly constrained range 0.5–0.833 μm, has been released by the ExoMol project, “C2018” (Coles et al. 2018), which demonstrates significant advantages over previously available datasets, and providing for the first time complete line data for the previously poorly constrained 5520- and 6475-?A bands of NH3. In this paper we compare spectra calculated using the ExoMol–C2018 dataset (Coles et al. 2018) with spectra calculated from previous sources to demonstrate its advantages. We conclude that at the present time the ExoMol–C2018 dataset provides the most reliable ammonia absorption source for analysing low to medium resolution spectra of Jupiter in the visible/near-IR spectral range, but note that the data are less able to model high-resolution spectra owing to small, but significant inaccuracies in the line wavenumber estimates. This work is of significance not only for solar system planetary physics, but for future proposed observations of Jupiter-like planets orbiting other stars, such as with NASA’s planned Wide-Field Infrared Survey Telescope (WFIRST).
关键词： ammonia,ExoMol,visible spectrum,Jupiter,absorption,WFIRST,VLT,MUSE,C2018,NASA/Juno
更新于2025-09-04 15:30:14