Browsing by Author "CHERN, HN"

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AN ANALYTICAL MODEL FOR THE ABOVE-THRESHOLD CHARACTERISTICS OF POLYSILICON THIN-FILM TRANSISTORS
(1995-07-01)
CHERN, HN
;
LEE, CL
;
LEI, TF
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
An analytical model for the above-threshold characteristics of long-channel, small-grain and thin channel polysilicon thin film transistors (TFT's) is presented. This model is constructed by considering the barrier potential and the carrier trapping effect at grain boundaries of the channel. A band tail state located at E(c) - 0.15 eV is taken into account to simulate the I-V characteristics. Based on the model, the theoretically simulated results show good agreement with the experimental data of the plasma-passivated and unpassivated TFT devices in a wide range of the gate, drain biases and the temperature. The correlation of the transconductance to the gate bias is also investigated, It is found that the decrease of grain-boundary barrier potential with the gate voltage enhances the transconductance, while this enhancement effect becomes insignificant and causes the decrease of the transconductance at the high gate bias.
CORRELATION OF POLYSILICON THIN-FILM-TRANSISTOR CHARACTERISTICS TO DEFECT STATES VIA THERMAL ANNEALING
(1994-03-01)
CHERN, HN
;
LEE, CL
;
LEI, TF
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Based on the response of electrical characteristics of hydrogenated polysilicon thin-film transistors (TFT's) to post-hydrogenation thermal annealing, the relationship of device parameters to deep states and tail states are distinguished. The deep states which affect the threshold voltage and subthreshold swing recover quickly, while the tail states which influence the leakage current and field effect mobility respond to the thermal annealing only after the annealing temperature exceeds 375 degrees C for 30 min.
H-2/O-2 PLASMA ON POLYSILICON THIN-FILM TRANSISTOR
(1993-03-01)
CHERN, HN
;
LEE, CL
;
LEI, TF
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This letter reports that the H-2 plasma followed by the O2 plasma is more effective to passivate grain boundary states in the polysilicon thin film. Polysilicon thin-film transistors (TFT's) made after applying H-2/O2 Plasma treatment can exhibit a turn-on threshold voltage of -0.1 V, a subthreshold swing of 0.154 V/decade, an ON/OFF current ratio I(on)/I(off) over 1 x 10(8), and an electron mobility of 40.2 cm2/V . S.
IMPROVEMENT OF POLYSILICON OXIDE CHARACTERISTICS BY FLUORINE INCORPORATION
(1994-05-01)
CHERN, HN
;
LEE, CL
;
LEI, TF
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The effect of fluorine on the polysilicon oxide (polyoxide) characteristics is investigated. It is found that the polyoxide leakage current and breakdown strength are improved as fluorine is incorporated into the oxide film. Experimental results show that the improvement is believed to be due to the oxide stress relaxation rather than the change of the polyoxide/polysilicon interface texture.
RADIATION EFFECTS ON N-CHANNEL POLYCRYSTALLINE SILICON THIN-FILM TRANSISTORS
(1995-12-04)
YANG, CK
;
LEE, CL
;
LEI, TF
;
CHERN, HN
;
電子工程學系及電子研究所
The radiation effect on the n-channel polycrystalline silicon (polysilicon) thin-him transistors has been investigated. It is found that for an unhydrogenated device, the irradiation of Co-60 With a total dose of 1 Mrads caused a negative threshold-voltage (V-th) shift and a slight subthreshold-swing (S) degradation, while for a hydrogenated n-channel device, the same irradiation results in a positive V-th Shift and a serious S degradation. It is also found that the radiation hardness of the hydrogenated devices can be improved somewhat by a simple irradiation-then-hydrogenation treatment. (C) 1995 American Institute of Physics.
THE EFFECTS OF FLUORINE PASSIVATION ON POLYSILICON THIN-FILM TRANSISTORS
(1994-05-01)
CHERN, HN
;
LEE, CL
;
LEI, TF
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The fluorine implantation on polysilicon was found to improve the characteristics of polysilicon thin-film transistors (TFT's). The fluorine passivates the trap states within the polysilicon channel. As compared with the H-2-plasma passivation, the fluorine implantation passivates more uniformly both the band tail-states and midgap deep-state, while the H-2-plasma treatment is more effective to passivate deep states than tail states. A fluorine-implanted device can be further improved its performance if an H-2-plasma treatment is applied. In contrast to the H-2-plasma passivation, the fluorine passivation improves the device hot-carrier immunity. Combining the fluorine passivation and H-2-plasma passivation, a high performance TFT with a high hot-carrier immunity can be obtained.
THE EFFECTS OF H-2-O-2-PLASMA TREATMENT ON THE CHARACTERISTICS OF POLYSILICON THIN-FILM TRANSISTORS
(1993-12-01)
CHERN, HN
;
LEE, CL
;
LEI, TF
;
電子工程學系及電子研究所
;
奈米中心
The effects of H-2-plasma followed by O-2-plasma treatment on n-channel polysilicon TFT's were investigated. It was found that the H-2-O-2-plasma treatment is more effective in passivating the trap states of polysilicon films than do the H-2-plasma treatment only or the O-2-plasma treatment only. Hence, it is more effective in improving the device performance on the subthreshold swing, carrier mobility and the current ON/OFF ratio. It is also found that thermal annealing on plasma-treated devices increases the deep states but has no effect on the tail states of the devices.