In this work, polycrystalline silicon (poly‐Si) thin films were fabricated by aluminum induced crystallization (AIC) technique. SiNx, deposited as a function of NH3/SiH4 ratio, and AZO (Al‐doped ZnO) films on glass were used as a buffer layer between glass and Si film. The effect of buffer layer content on the crystallinity of poly‐Si thin films was studied by Raman analysis which shows that fully crystallization without stress was achieved for all samples. Moreover, the preferred crystalline orientation and crystallite size of films were deduced by X‐ray diffraction (XRD) analysis. The preferred orientation is <100> as independent from the buffer layer content while the crystallite sizes increase up to 48.5 nm by increasing the amount of SiH4. The electrical properties of the films were carried out by four point probe and current–voltage (I–V) analysis. Both techniques demonstrated that the resistivity of the SiNx‐based samples is around 0.1 Ωcm. The grain size analysis was accomplished by electron back scattering diffraction (EBSD) measurements. The grain size up to 25 µm was achieved as observed from EBSD images. The results show that the fabrication parameters of SiNx and AZO buffer layers have the great effects on the crystallography of poly‐Si films.
Aluminum-induced crystallization (AIC) experiments were carried out in order to investigate the influence of vacuum annealing of the Al layer at 500 8C prior to deposition of e-beam evaporated amorphous silicon (a-Si). A control sample set using the identical deposition sequences but without the Al vacuum anneal was also produced as reference. Analysis revealed that after vacuum annealing, the Al grain size increases significantly. The surface Aloxide layer thickness is reduced, however, the Al-oxide to metallic Al ratio is increased in this layer. Following a-Si deposition, the a-Si/Al/SiN x /glass stacked samples were annealed in N 2 atmosphere at temperatures between 420 and 450 8C. It was seen that the crystal growth rate in the samples with vacuum-annealed Al is significantly reduced compared to the control samples, due to the reduction of Al grain boundary density.
The
laser crystallization (LC) of amorphous silicon thin films
into polycrystalline silicon (pc-Si) thin films on glass substrates
is an active field of research in the fabrication of Si-based thin
film transistors and thin film solar cells. Efforts have been, in
particular, focused on the improvement of LC technique. Adhesion promoters
of the crystallized Si thin films at the glass interface play a crucial
role in the stability and device performance of fabricated structures.
The crystalline Si thin films are required to be produced free of
contamination risks arising from impurity diffusion from the glass
substrate. Moreover, it is preferable to fabricate pc-Si thin films
at temperatures as close as possible to the ambient temperature for
an effective cost reduction. In this work, we demonstrate the successful
use of a commercially available nanosecond pulsed laser marker at
1064 nm wavelength for Si crystallization at ambient conditions compared
to the common method of pre-elevated substrate temperatures used in
continuous wave laser irradiation technique. As a result, our technique
results in a better energy balance than that in previous works. The
second main purpose of this study is to enhance the crystallinity
of Si thin films and to determine the best choice of an intermediate
dielectric layer (IDL) comparatively among four thin buffer layers,
namely, SiN
x
, SiO
2
, ZnO, and
TiO
2
, for the sake of obtaining improved adhesion and larger
crystalline domains as compared to that on a direct Si–glass
interface. The crystalline qualities of samples containing IDLs of
SiN
x
, SiO
2
, ZnO, and TiO
2
were compared via Raman spectroscopy analysis and electron
backscatter diffraction method against the direct Si–glass
interface reference. The analyses quantitatively showed that both
the crystallinity and the domain sizes can be increased via IDLs.
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