In situ x-ray studies of the incipient ZnO atomic layer deposition on In0.53Ga0.47As

Abstract

We describe in detail how ZnO films grow on In0.53Ga0.47As substrates by Atomic Layer Deposition (ALD), employing a suite of in situ synchrotron X-ray techniques. Combining results from different measurements allows the distinguishment of three different growth behaviors: an initial, slow linear growth, often referred to as a growth delay (regime I), followed by a nonlinear growth (regime II), and finally, a steady, linear growth (regime III), the last of which is the self-limited growth behavior characteristic of ALD. By the end of the regime I, the In0.53Ga0.47As surface is covered with an ultra-thin, poorly-ordered Zn oxide layer. The transition from regime I to II is clearly evidenced by the appearance on the X-ray absorption spectra of characteristic features of the wurtzite structure, as well as the nucleation and growth of ZnO grains (3D) on top of the poorlyordered Zn oxide layer. Regime II ends when the growth per cycle reaches a constant level. We show that the water pressure during growth has an impact on the duration of the growth delay (regime I), unlike the substrate temperature. In the regime of steady growth, we observe that the rate of deposition obtained for all temperatures inside the ALD window is 0.17 nm.cy −1. The deposition temperature has clear effects on the film texture and initial crystallization behavior, as well as the final crystallinity and thicknesses of the layers adjacent to the In0.53Ga0.47As substrate. Based on the experimental results and earlier ab initio calculations and Monte Carlo simulations of ZnO ALD on ZnO, we suggest reaction mechanisms consistent with our findings and present a model of growth starting from the very earliest stages of deposition to the steady growth regime.

In Situ Ellipsometry Study of the Early Stage of ZnO Atomic Layer Deposition on In0.53Ga0.47As

“…ZnO growth on either InGaAs or ZnO surface is very different . ZnO ALD on ZnO has been the subject of experimental works and more recently of density functional theory and Monte Carlo simulations .…”

“…Using synchrotron radiation techniques for the monitoring of ZnO ALD on (hereinafter InGaAs), we put in evidence that the initial ZnO growth on InGaAs is very different from the ideal layer‐by‐layer ZnO growth on ZnO. We demonstrated the presence of two successive growth regimes preceding the steady ZnO ALD.…”

In situ ellipsometry monitoring of TiO2 atomic layer deposition from Tetrakis(dimethylamido)titanium(IV) and H2O precursors on Si and InSkopin1, Abdukayumov2, Younes3 et al. 2021Thin Solid FilmsSelf Cite7010View full textAdd to dashboardCite

“…1S and Table T1 in the Supplementary Information file). More information about ellipsometry measurements with the same equipment and software can be found in a previous study [35].…”

“…Here, we report on a parametrical study to optimize TiO 2 ALD in our custom-built reactor [40,34,36,35,41,37]. The main process parameters were varied, i.e.…”

“…Despite the significant number of publication reporting on TiO 2 ALD from TDMAT and water [12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,31,33], there is no clear idea of all the possible chemical reactions on the surface during the growth process and also there is no unique behavior of growth curves (Growth Per Cycle) as a function of the growth temperature. Additionally, it was shown that the TiO 2 initial growth stages depend on substrate chemistry, as in the case of ZnO ALD [34,35,36,37], TiO 2 exhibit different types of growth depending on the surface [15,29].…”