Baryshnikova Marina, Boelen Andries, Ceccon Luca, Herreman Vincent, McMitchell Sean R C, Haffner Christian, Merckling Clement
Imec, Kapeldreef 75, 3001 Leuven, Belgium.
Department of Materials Engineering, KU Leuven, Kasteelpark Arenberg 44, 3001 Leuven, Belgium.
Materials (Basel). 2024 Apr 9;17(8):1714. doi: 10.3390/ma17081714.
In this study, we investigate the changes in the crystalline structure of MBE-deposited SrTiO layers on Si with different deviations from Sr/Ti stoichiometry as deposited but also after annealing at high temperatures (>600 °C). We show that as-grown 15 nm thick non-stochiometric SrTiO layers present surprisingly lower FWHM values of the (002) omega diffraction peak compared to fully stoichiometric layers of similar thickness. This can misleadingly point to superior crystalline quality of such non-stochiometric layers. However, thermal post-deposition anneals of these layers at temperatures up to 850 °C in oxygen show strong detrimental effects on the crystalline structure, surface and interface with the Si (001) substrate. On the contrary, the post-deposition anneals applied to the stoichiometric samples strongly improve the physical, optical and electrical properties of the epitaxial SrTiO thin films.
在本研究中，我们研究了分子束外延（MBE）在硅上沉积的SrTiO层的晶体结构变化，这些层在沉积时以及在高温（>600°C）退火后具有不同程度偏离Sr/Ti化学计量比的情况。我们表明，与类似厚度的完全化学计量比的层相比，生长态的15纳米厚非化学计量比SrTiO层的（002）ω衍射峰的半高宽（FWHM）值出奇地低。这可能会误导性地表明这种非化学计量比层具有优异的晶体质量。然而，这些层在氧气中高达850°C的温度下进行热沉积后退火，对晶体结构、表面以及与Si（001）衬底的界面都有强烈的不利影响。相反，对化学计量比样品进行的沉积后退火极大地改善了外延SrTiO薄膜的物理、光学和电学性能。
