CdZnTe thin films were deposited on FTO (SnO<sub>2</sub>: F)-coated glass substrates by close-spaced sublimation method and then annealed under three different conditions. The influences of the three thermal treatments on the structure, morphology, composition and optical properties of the CdZnTe thin films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy disperse spectra (EDS) and photoluminescence (PL) spectroscopy. The XRD results show that the films are (111) preferred orientation. The SEM and PL spectroscopy results show the better crystalline quality after any of three thermal treatments than that of as-deposited sample. The EDS analysis indicates that the Zn composition decreases for the sample with CdCl<sub>2</sub> annealing, but increases for the sample annealing directly and ZnCl<sub>2</sub> annealing. The same results are also obtained by XRD and PL spectroscopy.
CsMX<sub>3</sub>(M = Sn, Pb; X = Cl, Br, I) are strong candidates for the fast high energy irradiation detectors, ionic conductors, and optoelectronic devices. There are many experimental and theoretical investigations devoted to the study of perovskites ABX<sub>3</sub> (A is a cation with different valence, B is a transition metal and X is oxides, halides or chlorides). But there is no systematic study of CsMX<sub>3</sub> using HSE approximation particularly. In this paper, the band structures, density of states and optical properties of CsMX<sub>3</sub>(M = Sn, Pb; X = Cl, Br, I) have been studied by first-principles calculations using both the hybrid functional (HSE) approximation and the PBE-GGA approximation. The results of both approximations are compared with the experimental values. The results of HSE are closer to the experimental values. The changes of properties have been founded by comparing the band structures, density of states and optical properties of this series of thin film materials respectively. The trend of impact on these properties by replace elements has also been found. Our results provide a basis for the design of specific performance thin film materials.
The Si overlayers were grown by solid phase epitaxy on the atomically smooth Er<sub>2</sub>O<sub>3</sub> (111) films, which is prepared on
the Si (111) substrate in optimum conditions. The twin structure was observed in the spot-like reflective high energy
electron diffraction (RHEED) patterns. The rough surface of Si overlayer, as identified by both RHEED results and
Atomic force microscopy (AFM) images, indicated a three dimensional growth mode in contrast to the two dimensional
growth mode of Er<sub>2</sub>O<sub>3</sub> on the Si (111) substrate. The physical origin of three dimensional grow is given based on the
interfacial energy argument.
200 μm thick free-standing polycrystalline diamond film has been grown by microwave plasma chemical vapor deposition (MPCVD) method. The nucleation surface of diamond is characterized by Raman scattering, scanning electron microscopy (SEM) and atomic force microscopy (AFM) method. AFM and SEM results indicate the nucleation
surface is quite smooth with a mean surface roughness (RMS) of about 10 nm. Raman scattering result indicates of high quality nucleation diamond film. A diamond field effect transistor is fabricated on hydrogenated diamond nucleation surface, using standard lithographic procedures. Device with aluminum (Al) gate electrode, to form Schottky barrier with diamond, as well as Au source and drain electrodes to form ohmic contact with diamond, operates as effective
enhancement-mode metal-semiconductor field-effect transistors at room temperature, showing clear modulation of channel current.
A hot filament chemical vapor deposition (HFCVD) apparatus, combined with a cyro-cooled superconductor magnet,
were recently developed. Nanocrystalline diamond (NCD) films were prepared by above HFCVD apparatus either with
or without high magnetic field. Surface morphologies of these films were characterized by means of atomic force
microscope (AFM). The results indicated that the mean surface roughness and grain size of these films decreased when
the magnetic field varied from 0T to 4T. From Raman scattering measurement, all films prepared either with or without
high magnetic field exhibit NCD features. These NCD features of the sample prepared with 4T magnetic field was
obviously pronounced. The structure of these films was also investigated by X-ray diffraction (XRD).
The structure, electrical and optical properties of nano-crystalline diamond (NCD) films deposited by hot-filament
chemical vapor deposition (HFCVD) method, are reported. The influence of the carbon concentration during the film
deposition on the Raman scattering, optical gap, optical constants (<i>n</i> and <i>k</i>) and dark-current is investigated. Under a
higher carbon concentration during deposition, the NCD film obtained with a smaller grain size, has a lower optical gap,
refractive index and electrical resistivity. These changes with the carbon concentration are attributed to the high amount
of sp<sup>2</sup> bonded carbons and other non-diamond phase, which is confirmed by Raman scattering measurements.
A heterostructure of nanocrystalline diamond film / n-Si was fabricated successfully, where the un-doped p-type
nanocrystalline diamond (NCD) film was grown by an electron assisted hot filament chemical vapor deposition (EA-HFCVD)
technology. The structure and morphology of the NCD film were analyzed by Raman spectroscopy, X-ray
diffraction (XRD) and scanning electron microscopy (SEM). I-V characteristic of the p-NCD/n-Si heterojunction
indicated that this structure was rectifying in nature with a turn-on voltage of ~0.5V. The p-NCD/n-Si heterostructure
was also used for UV detector applications. Operating at a bias voltage of 10V, this photodetector showed a significant
discrimination between UV and visible light, and the UV/visible-blind ratio was about three orders of magnitude.