In Situ Ellipsometry Study of the Early Stage of ZnO Atomic Layer Deposition on In_0.53Ga_0.47As

Abstract

The initial stages of ZnO atomic layer deposition (ALD) on In0.53Ga0.47As (InGaAs) are studied by monitoring the ZnO film thickness in situ with spectroscopic ellipsometry. Using diethylzinc (DEZn) and water, at a substrate temperature equal to 120 °C, the presence of two different ZnO growth regimes prior to steady growth is found: a slow ZnO nucleation on InGaAs, 0.005 nm.cy−1 (growth delay), then a substrate‐inhibited growth of type II. Increasing the DEZn injection time, the growth delay shortens from 30 cycles down to 3 cycles; concomitantly, the steady growth rate increases from 0.18 to 0.23 nm.cy−1. The DEZn residence time and pressure increase during the first ALD cycle, allowing to suppress growth delay; instead, no change is observed when performing the same experiment with water. Atomic force microscopy (AFM) images show that the InGaAs surface roughens after the first cycle with a long DEZn pulse and residence time. The rough surface is likely at the origin of the growth delay elimination.

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 Films7010View full textAdd to dashboardCite

“…In our previous ALD study [34,35,36,37], we showed that the early stage of growth of ZnO ALD on (100)InGaAs surface from Diethylzinc and water, is a substrate-inhibited growth of type 2, as in the case of TiO 2 ALD on (100)In-GaAs. As for TiO 2 ALD on InGaAs, the most likely explanation for the GPC behavior in the early stage of growth, is the surface roughening (see inset of Fig.…”

“…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].…”

Initial Growth and Crystallization Onset of Plasma Enhanced-Atomic Layer Deposited ZnO

“…Recently in the literature, great attention has been given to the initial stages of growth of ZnO by thermal ALD [23][24][25][26][27][28][29][30]. Understanding the first stages of growth is of particular importance when ultrathin and continuous ZnO films are required, e.g., as an electron buffer layer for inverted solar cells [4], or as a passivation layer in transistors [31,32].…”

“…Compared to the initial growth stages, the onset of crystallinity has not received the same attention. In a series of investigations on thermal ALD ZnO, Renevier, Ciatto et al reported on the growth of ZnO when deposited on different substrates (a-SiO 2 [26][27][28], c-Al2O3 [26][27][28], In 0.53 Ga 0.47 As [29,30]). The in-situ methodology adopted (mainly X-ray based methods, such as X-ray fluorescence and X-ray absorption near-edge structure spectroscopy) identified the onset of crystallization to start from the very first cycle when deposited on c-Al 2 O 3 , adopting a 2D-like growth and developing in-plane crystallinity; a different growth behavior was instead observed when deposited on a-SiO 2 and In 0.53 Ga 0.47 As, on which the crystallinity starts after the development of an initial amorphous layer.…”