A heterojunction with good rectifying properties in a wide temperature range from 20 K to 300 K was fabricated simply by depositing an as-grown La<sub>0.9</sub>Hf<sub>0.1</sub>MnO<sub>3</sub> (LHMO) film on a commercial 0.7 wt% Nb-doped SrTiO<sub>3</sub> single crystal substrate using pulsed laser deposition technique. The current-voltage behavior of the LHMO/STON is measured under applied magnetic fields varying between 0 and 5 T. The heterojunction shows a remarkable magnetoresistance which depends on both the temperature and bias voltages. The sign of the magnetoresistance as function of temperature at either forward or reverse bias voltage is extensively studied by the filling of electrons in the e<sub>g</sub> and t<sub>2g</sub> band. The good rectifying behaviors, the magnetic tunable properties and the maximum magnetoresistance obtained at room temperature make this simple heterojunction promising for practical applications.
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.
Cu<sub>2</sub>S thin films have been deposited on CdS/ITO (In<sub>2</sub>O<sub>3</sub>:Sn) substrates with various substrate temperatures by DC magnetron sputtering method. The effects of substrate temperature on the crystallization behavior and morphology are studied. Chemical composition of the films is confirmed by energy dispersive X-ray (EDX) spectroscopy. X-ray diffraction (XRD) analysis of the films reveals they have polycrystalline chalcocite structure with (110) texture. Field emission scanning electron microscopy (FESEM) show the crystalline nature of the films at higher substrate temperature, which is in accordance with XRD measurements. Stoichiometric analysis exhibits element composition with Cu/S concentrations ratio equal to 2 approximately.
Semiconductor detector that incorporate neutron reactive material within the same detector demonstrates a new method for neutron dosimetry and boron neutron reactive therapy seems to be a promising treatment. Boron films were deposited on single crystalline silicon, glass, and CVD diamond film by magnetron sputtering, close-space sublimation and vacuum evaporation. The properties of the samples were characterized by SEM, which shows vacuum evaporation method is suitable for depositing high quality boron films.
ZnO/diamond film heterojunction diodes were fabricated by depositing n-type ZnO films on p-type freestanding
diamond (FSD) films using radio-frequency (RF) magnetron sputtering method. The effects of the annealing process on
the properties of ZnO films were studied. The influence of the annealing process on the current-voltage (I-V)
characteristics of the electrodes on ZnO and diamond films and the property of heterojunction diode was also examined.
The results showed that the annealing treatment was helpful to improve the crystalline quality of the films and the
performance of the diode.
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.
In this work, an Al-N-co-doped p-type ZnO film was deposited on the smooth nucleaction side of freestanding diamond
film by radio-frequency (RF) reactive magnetron sputtering method. An intrinsic n-type ZnO layer was deposited on the
p-type Al-N-co-doped ZnO film to fabricate ZnO p-n homojunction. The electrical properties of ZnO p-n homojunction
in dark condition were investigated by a Keithley 4200/SCS digital semiconductor characterization system. The result
exhibited the distinct rectifying current-voltage (I-V) characteristics with a turn-on voltage of ~2.2V. The homojunction
was also used for UV photodetector application. Spectral response of the detector showed a significant discrimination
between UV and the visible light.
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.
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 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).
Nanocrystalline diamond (NCD) films have been deposited by hot filament chemical vapour deposition (HFCVD) from
acetone/hydrogen gas mixtures on a variety of substrates such as silicon wafers and polycrystalline diamond. The
influence of the chemical nature of the substrate, the roughness, and the pretreatment of the substrates on the nucleation
and the bulk structure of the NCD films are investigated. By means of X-ray diffraction (XRD) and Raman spectroscopy
it is shown that the bulk properties of the films are not affected by the status of the substrate although these have a strong
influence on the nucleation behaviour.
Nanocrystalline diamond(NCD) films with a mean surface roughness of 23.8 nm were grown on silicon substrates in a
hot filament chemical vapor deposition(HFCVD) system. Then,
Zn<sub>1-x</sub>Li<sub>x</sub>O (<i>x</i>=0, 0.05, 0.10, 0.15) films were deposited on
these NCD films by radio-frequency(RF) reactive magnetron sputtering method. When x was 0.1, the Li-doped ZnO film
had a larger resistivity more than 10<sup>8</sup>Ω•cm obtained from Hall effect measurement. All the Zn<sub>1-x</sub>Li<sub>x</sub>O films had a strong
<i>c</i>-axis orientation structure determined by X-ray diffraction (XRD). The above results suggested that the Li-doped ZnO
film/NCD structure prepared in this work was attractive for the application of high frequency surface acoustic wave
The free-standing diamond films with a smooth and high quality nucleation side were prepared by hot filament chemical
vapor deposition (HFCVD) method. The nucleation side of the films had a mean surface roughness of 1.6nm.AlN films
were then deposited on the nucleation side of the above diamond films by radio-frequency (RF) reactive magnetron
sputtering method. The structure characteristics of AlN films deposited under different working pressure (<i>p</i>), sputtering
power (<i>w</i>) and sputtering plasma composition were studied. The optimized parameters for the growth of high <i>c</i>-axis
orientation AlN films were obtained: <i>p</i>=0.2Pa,<i>w</i>=600w and Ar/N<sub>2</sub>=3:1.Surface morphologies of AlN films deposited
under these parameter, tested by means of atomic force microscope (AFM), showed that the mean surface roughness was
about 4.1nm.It also had a strong c-axis orientation structure investigated by X-ray diffraction (XRD). All results above
suggested that the AlN/diamond structure prepared in this work was ideal for the application of high frequency surface
acoustic wave devices (SAW) device.