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Conducting oxide interfaces have attracted considerable attention, motivated by both fundamental science and potential for oxide electronic devices. An important gap for maturing such device technology is scalability and routes to control the electronic properties, which can narrow the device engineering space. Here, we demonstrate and explain the mechanisms of highly tunable conductive oxide interfaces. We synthesized amorphous--crystalline Al2O3/SrTiO3 interfaces using the scalable and industry-compatible atomic layer deposition (ALD) technique. An NH3 plasma pretreatment is employed in the ALD chamber, and its duration is used as a tuning parameter for the electrical properties, where a span of three orders of magnitude in the sheet resistance is observed at room temperature. For the most conductive sample, our results are comparable to the highest carrier density values reported for all-crystalline oxide interfaces prepared with state-of-the-art epitaxial growth techniques, such as pulsed laser deposition. We pinpoint the origin of conductivity to oxygen vacancies caused by the SrTiO3 reduction by the NH3 plasma pretreatment. These results present a simple, scalable, and industry-compatible route for realizing conductive oxide interfaces, with a broad parameter space, offering a versatile and flexible toolkit for oxide device engineering. [ABSTRACT FROM AUTHOR]

Heterojunction device performance has strong dependence on its junction interface. ZnO deposition over GaN to achieve a heterojunction is challenging as it usually requires high temperature and vacuum processing. It is even more demanding to achieve a crystalline interface while making ZnO nanorod based heterojunction. Here we report simple solution process for epitaxial growth of ZnO nanorods over GaN. High resolution x-ray diffraction studies revealed highly crystalline c-axis oriented ZnO nanorod growth by a simple hydrothermal process. ZnO/GaN heterojunction device fabricated using hydrothermally synthesized ZnO nanorods showed superior performance compared to polycrystalline sputter deposited ZnO based heterojunction. [ABSTRACT FROM AUTHOR]

Heusler compounds, in both cubic and hexagonal polymorphs, exhibit a remarkable range of electronic, magnetic, elastic, and topological properties, rivaling that of the transition metal oxides. To date, research on these quantum materials has focused primarily on bulk magnetic and thermoelectric properties or on applications in spintronics. More broadly, however, Heuslers provide a platform for discovery and manipulation of emergent properties at well-defined crystalline interfaces. Here, motivated by advances in the epitaxial growth of layered Heusler heterostructures, I present a vision for Heusler interfaces, focusing on the frontiers and challenges that lie beyond spintronics. The ability to grow these materials epitaxially on technologically important semiconductor substrates, such as GaAs, Ge, and Si, provides a direct path for their integration with modern electronics. Further advances will require new methods to control the stoichiometry and defects to "electronic grade" quality and to control the interface abruptness and ordering at the atomic scale. [ABSTRACT FROM AUTHOR]

The properties of the interface between crystalline silicon (c-Si) and amorphous silicon (a-Si) were studied for two deposition methods of a-Si. One is the conventional plasma enhanced chemical vapor deposition (PECVD) and the other is catalytic chemical vapor deposition (Cat-CVD), often called hot-wire CVD. Surface recombination velocity (SRV) and atomic scale fine structure at the a-Si/c-Si interface were particularly studied. It is found that the a-Si/c-Si interface is very sharp for Cat-CVD a-Si and the width of transition-layer from c-Si to a-Si is less than 0.6 nm, which is three times smaller than for PECVD a-Si. It is also found that the SRV for Cat-CVD a-Si is about 1/3 of that for PECVD, and that the SRV appears to depend on the effective area of the interface which increases due to increase of surface roughness caused by plasma damage. [ABSTRACT FROM AUTHOR]

GaAs epilayers on Ge substrates are grown with a thin Al0.3Ga0.7As interlayer via metal-organic chemical vapor deposition with the goal of investigating the effect of the Al0.3Ga0.7As interlayer thickness upon the GaAs epilayer. The results show that as the Al0.3Ga0.7As interlayer thickness increases from 0 to 30 nm, both the crystal quality and surface morphology of the GaAs epilayer follow a trend of melioration and then deterioration. All of the Al0.3Ga0.7As interlayers investigated are seen to effectively block the diffusion of Ge atoms to the GaAs epilayers, and high crystalline quality GaAs epilayers with a smooth surface are obtained by growing a 15-23 nm-thick Al0.3Ga0.7As interlayer. [ABSTRACT FROM AUTHOR]