Temperature effect on (2 + 1) experimental Kardar-Parisi-Zhang growth

Abstract

PACS 68.43.Hn -Structure of assemblies of adsorbates (two-and three-dimensional clustering) PACS 81.15.Aa -Theory and models of film growth PACS 05.40.-a -Fluctuation phenomena, random processes, noise, and Brownian motion Abstract -We report on the effect of substrate temperature (T ) on both local structure and long-wavelength fluctuations of polycrystalline CdTe thin films deposited on Si(001). A strong T -dependent mound evolution is observed and explained in terms of the energy barrier to intergrain diffusion at grain boundaries, as corroborated by Monte Carlo simulations. This leads to transitions from uncorrelated growth to a crossover from random-to-correlated growth and transient anomalous scaling as T increases. Due to these finite-time effects, we were not able to determine the universality class of the system through the critical exponents. Nevertheless, we demonstrate that this can be circumvented by analyzing height, roughness and maximal height distributions, which allow us to prove that CdTe grows asymptotically according to the Kardar-Parisi-Zhang (KPZ) equation in a broad range of T . More important, one finds positive (negative) velocity excess in the growth at low (high) T , indicating that it is possible to control the KPZ non-linearity by adjusting the temperature.

Initial pseudo-steady state & asymptotic KPZ universality in semiconductor on polymer deposition

“…1(b)]. Interesting, the asymptotic pyramidal morphology resembles the typical KPZ-CdTe patterns observed during the growth of CdTe on Si(001) substrates 19, 21 . One-dimensional profiles of these two distinct regimes [Fig.…”

“…Hence, α  = 0.37(4) is our first strong evidence of KPZ scaling. As an aside, we point out that a clear scaling regime l g  ≪  l  ≪  ξ has not been observed for CdTe/Si(100) system 19, 21 , possibly due to the short growth times analyzed there, as is also the case of the samples grown up to 720 min here. This is one of the reasons why a consistent universal α exponent is rarely observed in real grained surfaces.…”

“…Subsequent work 36 called attention for the importance of considering window boundary conditions (WBC), which parallels the experimental way of obtaining P ( w 2 ). More challenging, the 2D distributions for WBC have been numerically investigated 20, 33, 37, 38 , and experimentally used to confirm the universality of CdTe/Si(001) 19, 21 , oligomer 20 and oxide 38 growing films. The successful agreement between numerical and experimental width distributions in 2D motivated their analysis also in 1D KPZ interfaces of nematic liquid-crystal system 7 .…”

Scaling of local roughness distributions

“…[20][21][22][23][24]. However, their accuracy is usually smaller than that of the variation coefficient C. Note that this is a particular feature of the LRDs in the growth regime because there is a crossover in the shape of the distribution at r/ξ ∼ 1.…”

“…[20] suggested a universal LRD for several KPZ models in 32 ≤ r ≤ 128 (measured in lattice units) after growth times 4000 ≤ t ≤ 8000 (measured in number of deposition trials). These values partly guided the choice of box size in the study of semiconductor films [21,22]. On the other hand, Halpin-Healy and Palasantzas argued that universal LRDs should be measured under the condition r ≪ ξ, where ξ is the lateral correlation length [23].…”