Epitaxial growth of rhombohedral β- and cubic γ-CuI

Epitaxial Growth of AgxCu1−xI on Al2O3(0001)

“…The near‐band‐edge optical emission properties of differently prepared layers were investigated by means of PL spectroscopy at 2 K. The corresponding PL spectra are shown for alloy compositions in Figure 4b. For binary CuI, the observed emission profile is comparable with our previous results [ 18 ] on thin films, which were grown at similar conditions. The emission lines at 3.065 eV and 3.055 eV can be assigned to free exciton–polariton emission from upper (UPB) and lower (LPB) polariton branches, respectively.…”

“…The values for the mobility are in the range from 12 to 15 cm 2 V −1 s −1 , which is characteristic for γ ‐CuI. [ 18,22 ] With increasing Ag content we observe a strong increase in resistivity of around three orders of magnitude from CuI to AgI. However, due to the surface morphology of especially Ag‐rich layers, no clear statement can be made about the charge carrier density and mobility as a function of the alloy composition.…”

“…On one hand, epitaxial layers were deposited using close distance sublimation (CDS), which was recently reported for the deposition of binary CuI. [ 18 ] Here, we used powder‐based pellets with defined chemical composition. For this, a mixture of CuI and AgI powders was pressed into a cylindrical shape, heated to 400 °C, and tempered for 4 min.…”

“…To study the phase formation of in the transition range of γ ‐ and β ‐phase and to grow thicker layers in the μm‐range with defined properties, a special sublimation technique was applied. [ 18 ] Thus, the main focus is on the deposition of as epitaxial layers, the structural stabilization of the γ ‐phase by CuI incorporation during epitaxial growth and determination of its growth window as a function of source composition. In addition, especially Ag‐rich thin films were synthesized using a solid‐state reaction on substrates allowing the fabrication of single‐phase γ ‐ layers on up to Ag content of .…”

Suppression of Rotational Domains of CuI Employing Sodium Halide Buffer Layers

“…Additionally, the halide semiconductor copper iodide (CuI) also attracted research interest, since it features a large and direct band gap ( E g = 3.1 eV) combined with high charge carrier densities up to p ≈ 10 20 cm –3 and hole mobilities up to μ = 44 cm 2 /(V s), resulting in highly conductive films while retaining a high transparency. − Further, the high excitonic binding energy ( E x b = 58 meV) renders it promising for various optoelectronic applications. At standard conditions, CuI usually crystallizes solely in the zinc-blende γ-phase with a complex phase diagram at high temperatures and pressures. , However, recently, an orthorhombic β-phase of CuI, previously attributed to be a high-temperature structure, stabilized at room temperature in conjunction with the γ-phase utilizing a close distance sublimation technique …”