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

## TL;DR

This study demonstrates the emergence of KPZ universality in CdTe film deposition on polymers, revealing a pseudo-steady state early on and confirming long-term KPZ behavior through experimental surface analysis.

## Contribution

It provides the first experimental evidence of a pseudo-steady state and confirms the asymptotic KPZ universality in semiconductor-on-polymer deposition.

## Key findings

- Observation of a pseudo-steady state in early deposition stages
- Confirmation of KPZ universality at long times
- Experimental validation of theoretical scaling and distribution predictions

## Abstract

The Kardar-Parisi-Zhang (KPZ) class is a paradigmatic example of universality in nonequilibrium phenomena, but clear experimental evidences of asymptotic 2D-KPZ statistics are still very rare, and far less understanding stems from its short-time behavior. We tackle such issues by analyzing surface fluctuations of CdTe films deposited on polymeric substrates, based on a huge spatio-temporal surface sampling acquired through atomic force microscopy. A \textit{pseudo}-steady state (where average surface roughness and spatial correlations stay constant in time) is observed at initial times, persisting up to deposition of $\sim 10^{4}$ monolayers. This state results from a fine balance between roughening and smoothening, as supported by a phenomenological growth model. KPZ statistics arises at long times, thoroughly verified by universal exponents, spatial covariance and several distributions. Recent theoretical generalizations of the Family-Vicsek scaling and the emergence of log-normal distributions during interface growth are experimentally confirmed. These results confirm that high vacuum vapor deposition of CdTe constitutes a genuine 2D-KPZ system, and expand our knowledge about possible substrate-induced short-time behaviors.