Jan Jurusik

Electron microscope investigations of the growth morphology of cadmium arsenide films vacuum deposited at various substrate temperatures

Abstract The growth conditions for Cd 3 As 2 films 0.1–17 μm thick obtained by thermal vacuum deposition were examined. The films were deposited onto NaCl substrates held at temperatures in the range 300–480 K. The platinum-shadowed carbon replica method was used for an electron microscope investigation of the surfaces and cross sections of the films. The microstructure of the films was strongly dependent on the temperature T s of the substrate.For T s below about 400 K ( T s / T m ⪅ 0.4) the films were amorphous; they consisted of spherical clusters or elongated fibrous-like clusters, or were uniform with a large number of pores and cavities. For T s above 410 K the films were polycrystalline. For 0.4 T s / T m T s ≈ 410–460 K) columnar growth was observed, whilst for T s / T m ⩾ 0.5 ( T s ⩾ 460 K) films with large equiaxed crystallites and clearly marked grain boundaries were obtained. The results obtained were discussed using the Movchan-Demchishin and Tornton models of film growth.

Structure and growth morphology of thin amorphous films of cadmium arsenide

Abstract The effect of deposition conditions (type and temperature of the substrate, rate of deposition) on the growth structure of the very thin and thicker amorphous films of cadmium arsenide was investigated by meand of transmission electron microscopy. The island growth character of very thin films is reflected in the topography of the top surface of thicker films by their various internal growth structures influenced by deposition conditions. The growth defects and a simple geometrical growth model of the most frequently observed defects are presented.

Transmission electron microscopy investigation of the post-nucleation growth structure of amorphous cadmium arsenide thin films

Abstract The post-nucleation growth structure of amorphous cadmium arsenide thin films prepared by physical vapour deposition was investigated by transmission electron microscopy and the carbon replica method. The very thin cadmium arsenide films exhibit a very distinct island structure. The islands and also the growth elements in thicker films are connected by pores or very low density areas. These density fluctuations were determined by deposition conditions mainly by rate of deposition and type of the substrate, but they were very stable on post-deposition heat treatment. Thegrowth structure and its change with varying deposition conditions are considered qualitatively with the simple model where the growth structure evolves as a result of two superimposed growth stages, planar and in thickness.

Polyketanils: Preparation of π-Conjugated Polymer Bases from p-dibenzoylbenzene with Various Diamines. Protonation with DL-Camphor-10-sulfonic Acid

New luminescent materials - aromatic polyketanils (PKs) containing p-phenylene and biphenylene linkages in the backbone and electron-donating side-group substitutions have been synthesized via melt polycondensation (180°C, 24 h). Their structures were confirmed by elemental and spectral Fourier transform infrared, 13Cand 1H NMR, and ultraviolet-visible (UV-vis) analysis. All the PKs were solution-processable and thermally stable, making them potential candidate materials for applications in microelectronics and aerospace. These ketanil polymers showed high thermal stability and well-defined glass transition temperatures (T g). The temperature at which the polymers lose 10% of their weight (T 10) ranged from 420 to 520°C. Depending on the polymer structure, PKs showed T g values in the range of 133 to 244°C. Moreover, the polymers emit either blue radiation or green radiation depending on the mutual presence of conjugated and saturated chain segments. The HOMO/LUMO energy gap of the polymers was in the range of 2.74-2.19 eV. The photoluminescence properties of the PKs after protonation with DL-camphor-10-sulfonic acid (CSA) were tested. The structure formation of (PKs)1(CSA)2 complexes are discussed on the basis of 1HNMRspectroscopy.

The columnar microstructure of amorphous cadmium arsenide thin films

Abstract The columnar growth structure of amorphous cadmium arsenide thin films prepared by physical vapour deposition from crystalline Cd 3 As 2 and CdAs 2 as sources was investigated by transmission electron microscopy and the carbon replica method. Amorphous cadmium arsenide films exhibit the structure generally called columnar; however, films deposited from a Cd 3 As 2 source commonly reveal such structure even under normal-incidence (to the substrate) deposition. The evolution of columnar growth structure and its change under various deposition conditions are considered qualitatively in relation to post-nucleation island growth and the evaporation deposition process itself.