Browsing by Author "LIN, HY"

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ANOMALOUS DOPING BEHAVIOR OF IN-SITU BORON-DOPED POLYCRYSTALLINE SILICON DEPOSITED BY ULTRAHIGH-VACUUM CHEMICAL-VAPOR-DEPOSITION
(1993-09-13)
LIN, HC
;
LIN, HY
;
CHANG, CY
;
LEI, TF
;
WANG, PJ
The deposition of in situ heavily boron-doped polycrystalline silicon (poly-Si) films was studied using an ultrahigh vacuum/chemical vapor deposition system. Fully activated carrier concentrations up to 3X10(20) cm-3 were obtained for the as-deposited films grown at 550-degrees-C. For boron concentration beyond this level, the crystallinity of poly-Si films degraded with increasing boron concentration, which resulted in an anomalous rise in resistivity. This crystallinity degradation occurred at a higher rate for films grown on a SiO2 surface than those grown on an undoped poly-Si surface. It is attributed to the preferential adsorption of boron atoms on the SiO2 surface. Under a high B2H6 flux condition, a large amount of boron atoms would accumulate on the SiO2 Surface before the formation of Si nuclei, and thus disturbs the subsequent film deposition and grain growth processes.
CHARACTERISTICS OF POLYCRYSTALLINE FILMS GROWN BY ULTRAHIGH-VACUUM CHEMICAL-VAPOR-DEPOSITION SYSTEM
(1995-12-01)
LIN, HY
;
LEI, TF
;
LIN, HC
;
CHANG, CY
;
TWU, RC
In situ boron-doped polycrystalline Si1-xGex (poly-Si1-xGex) films deposited by ultrahigh vacuum chemical vapor deposition (UHV/CVD) system were characterized. Optimum fitted values of grain boundary trap state densities, 4.0 x 10(12) cm(-2) and 4.9 x 10(12) cm(-2) were obtained for poly-Si and poly-Si0.79Ge0.21, respectively. The extracted average carrier concentration in the grain agrees with secondary ion mass spectroscopy (SIMS) analysis. In turn, we found that these films are suitable Hall elements to sense magnetic field. Experimental results show that the sensitivity decreased with the increasing input current, which can be well explained using the thermionic emission theory. Finally, we use these films to fabricate thin film transistors.
DEPOSITION OF IN-SITU BORON-DOPED POLYCRYSTALLINE SILICON FILMS AT REDUCED PRESSURES
(1994-02-07)
LIN, HC
;
LIN, HY
;
CHANG, CY
;
LEI, TF
;
WANG, PJ
We report on the deposition of in situ boron-doped polycrystalline Si films on the SiO2 surface with reduced growth pressures at 550 degrees C. The deposition rate of these films decreased as the doping level was greater than 10(19) cm(-3). Such a result is in sharp contrast to what has been observed previously for similar films grown with conventional low pressure chemical vapor deposition techniques. It was also found that the incubation time prior to the deposition of these films diminished as the doping level was increased to 3x10(20) cm(-3) or higher. It is attributed to the preferential adsorption of boron atoms on the SiO2 surface at the initial stage of growth, which facilitates the nucleation of Si.
EFFECT OF BORON DOPING ON THE STRUCTURAL-PROPERTIES OF POLYCRYSTALLINE SILICON FILMS GROWN AT REDUCED PRESSURES
(1994-08-01)
LIN, HC
;
LIN, HY
;
CHANG, CY
;
JUNG, TG
;
WANG, PJ
The deposition and properties of in situ boron-doped polycrystalline silicon (poly-Si) films grown at 550-degrees-C were investigated using an ultrahigh vacuum chemical vapor deposition system. It is observed that, if the doping level is high enough, the boron incorporation would significantly reduce the deposition rate, impede the grain growth, and degrade the crystallinity of the poly-Si films. We also found that the preferential adsorption of boron atoms on the SiO2 surface at the initial stage of deposition shortened the incubation time of deposition. The property of trapping states at the grain boundary is also examined, and a density of about 4.7 X 10(12) CM-2 is obtained for poly-Si films with a doping level less than 2.2 X 10(19) cm-3.
EFFECTS OF SIH4, GEH4, AND B2H6 ON THE NUCLEATION AND DEPOSITION OF POLYCRYSTALLINE SI1-XGEX FILMS
(1994-09-01)
LIN, HC
;
CHANG, CY
;
CHEN, WH
;
TSAI, WC
;
CHANG, TC
In this study, the effects of different reactants, namely, SiH4, GeH4 and B2H6, on the nucleation and deposition of polycrystalline silicon-germanium (poly-Si1-xGe(x)) films on oxide surface in an ultrahigh vacuum chemical vapor deposition reactor were explored. The results show that the addition of GeH4 tends to retard the nucleation process of poly films while B2H6 is preferential for adsorbing on the oxide surface. These effects lead to different incubation duration depending on the kind of reactants used. On the deposition of poly-Si1-xGe(x) films, it is observed that the Ge incorporation is only slightly related to the substrate type, but the deposition mode of poly-Si1-xGe(x) films is much different from that of epitaxial growth on Si(100). The incorporation of Ge atoms also overcomes the anomalous doping effect encountered in heavily boron-doped poly-Si films and allows extremely low resistivity (below 2 mOMEGA-cm) poly films to be obtained at low temperatures (less-than-or-equal-to550-degrees-C).
FABRICATION OF P-CHANNEL POLYCRYSTALLINE SI1-XGEX THIN-FILM TRANSISTORS BY ULTRAHIGH-VACUUM CHEMICAL-VAPOR-DEPOSITION
(1994-09-26)
LIN, HC
;
JUNG, TG
;
LIN, HY
;
CHANG, CY
;
CHEN, LP
In this report, we present a novel approach for fabricating polycrystalline silicon-germanium thin-film transistors at low temperatures (less than or equal to 550 degrees C). A bottom gate configuration is used for this approach, and an i-Si1-xGex/i-Si/p(+)-Si1-yGey multilayer is deposited sequentially on the gate oxide using an ultra-high vacuum chemical vapor deposition technique. The i-Si1-xGex serves as the channel while the i-Si is used as a buffer layer for allowing p(+)-Si1-yGey to be etched selectively on. p-channel thin-film transistors with a held-effect mobility of 13 cm(2)/V s were achieved using this method, which is superior to those grown by low pressure chemical vapor deposition. Our results indicate that the deposition of poly-Si1-xGex/poly-Si multilayer structure would be a promising way for polycrystalline thin-film device applications.
GROWTH OF UNDOPED POLYCRYSTALLINE SI BY AN ULTRAHIGH-VACUUM CHEMICAL-VAPOR-DEPOSITION SYSTEM
(1993-09-06)
LIN, HC
;
LIN, HY
;
CHANG, CY
;
LEI, TF
;
WANG, PJ
Deposition of undoped polycrystalline-silicon (poly-Si) films on SiO2 using an ultrahigh vacuum chemical vapor deposition system was investigated. Poly-Si films with high crystallinity were obtained at a temperature as low as 525-degrees-C. The layer growth process was found to proceed with an activation energy of 44 +/- 2 kcal/mol, and is dominated by the desorption rate of surface-bonded hydrogen atoms. An incubation time was observed prior to the film deposition. This incubation period increased with decreasing growth temperature, resulting from slower nucleation and growth rates ai lower temperatures.
SPONTANEOUS FORMATION OF AL RICH AND GA RICH ALXGA1-XAS/ALYGA1-YAS SUPERLATTICE AND STRONG ENHANCEMENT OF OPTICAL-PROPERTIES
(1994-10-10)
CHIN, A
;
HSIEH, KY
;
LIN, HY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Long range composition ordering and spontaneous formation of Al rich and Ga rich AlxGa1-xAs/AlyGa1-yAs superlattice were demonstrated. This was observed by cross-sectional transmission electron microscopy (TEM) in a 280 angstrom Al0.4GaAs quantum well laser diode heterostructure with Al0.7GaAs barriers grown on (111)B GaAs substrates. On the contrary, none of above superstructure was observed by TEM on a side-by-side grown (100) oriented substrate. More evidence is shown in the (111)B Al0.7GaAs barriers which were disordered due to a high growth temperature and did not show any superstructure. 10 K photoluminescence was shown with 32 meV redshift and a 12-times peak intensity enhancement in (111)B orientation. (C) 1994 American Institute of Physics.
STRONG ENHANCEMENT OF THE OPTICAL AND ELECTRICAL-PROPERTIES, AND SPONTANEOUS FORMATION OF AN ORDERED SUPERLATTICE IN (111)B ALGAAS
(1995-05-01)
CHIN, A
;
LIN, HY
;
HSIEH, KY
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Strong enhancement in the luminescence intensity is observed in Al0.22Ga0.78As epitaxial layers grown on misoriented (111)B GaAs as compared to those simultaneously grown on (100) GaAs. For a 1 degrees misorientation the luminescence intensity is almost 10 to 1000 times that of the (100) layers, depending on the growth temperature. Room temperature electron mobility for 3 degrees misoriented (111)B Al0.18Ga0.82As is 19% higher than that for side-by-side grown (100). The strong luminescence associated with a large red shift of 90 meV and the 19% mobility enhancement are related to the long range composition ordering in (111)B AlGaAs, which is observed by cross-sectional transmission electron microscopy in a 280 Angstrom Al0.4GaAs quantum well heterostructure with Al0.7GaAs barriers grown on (111)B GaAs substrates.