Copper iodide (CuI) is an emerging high-performance ptype, wide-band-gap semiconductor. However, the growth mechanisms of CuI thin films and nanocrystals are currently unclear, as they do not follow the established models. In this work, the growth mechanisms and kinetics of sputtered CuI thin films were studied, which mainly depended on adatom/ substrate interface properties driven by growth temperature and rate. A modified structure zone model was proposed to explain the twodimensional layer-by-layer and three-dimensional island growth of CuI with different rates. The Wulff shape of the isolated CuI nanocrystals appeared to be controllable by the available iodine ion flux at high temperatures but low growth rates near the equilibrium. Moreover, smooth CuI thin films were successfully produced by combining a high substrate temperature with a high growth rate. A record-high hole mobility in a high carrier-density range was demonstrated, which was greater than twice the values reported previously. Our findings represent the essential steps toward advanced materials engineering and fabrication of CuI thin films for practical devices, as well as the selfassembly of shape-controlled CuI nano-and microcrystals.

We investigate the epitaxial growth of (Al,Ga)2O3 alloy thin films in the corundum phase on r-plane (01.2) Al2O3 substrates. We compare films grown by pulsed laser deposition at substrate temperatures of 750 °C and 1000 °C. The initial strongly anisotropic plastic strain relaxation through the a-plane prismatic glide system is directly evidenced by imaging the associated slip lines. We find enhanced plastic relaxation at the higher substrate temperature. Details of the stoichiometry transfer from the target to the film are discussed.

The growth of (AlxGa1-x)2O3 alloy thin films in corundum phase on r-plane (01.2) Al2O3 substrates is investigated. The growth mode changes from step flow for pseudomorphic layers to three-dimensional growth...

Anion doping is an efficient method for modifying the electrical property of the p‐type semiconductor CuI. However, adjustment of the hole density is still challenging. Using sputtering and spin coating techniques, well‐controlled S‐doping of CuI thin films has been realized. The spin‐coated samples present a single (111) out‐of‐plane orientation and very high crystallinity, which is comparable with previously reported epitaxial CuI thin films. The sputtered thin films have advantages in surface morphology and conductivity. Substituting S for I can achieve efficient acceptor doping of CuI for both the physical and chemical growth methods. The highest conductivity of CuI appears at 2.0 at% of S doping, and the doping efficiency is influenced by the self‐compensation effect.

Due to the textured nature of random in‐plane orientation of sputtered γ‐CuI (111) thin films, the crystalline grains and grain boundaries (GBs) influence charge carrier transport. Herein, current probe atomic force microscopy (cp‐AFM) measurements for differentiation and correlation of these morphological features and their contribution to electrical conductivity are presented, thus showing a clear difference between the conductive behavior of grains and GBs. A localized high and linearly voltage‐dependent current at the boundaries as well as a rectifying behavior between the platinum‐coated AFM tip and the grain surfaces is observed. Also, a different temporal evolution of voltage‐dependent conductivity is observed for grains and GBs. Further, the charge carrier transport through the surface vanishes with time. It is suspected that atmospheric oxygen causes these time‐dependent surface changes because accelerated degradation of the conductivity after oxygen plasma treatment is also measured.