Effect of Residual Phosphorus on Amorphous Silicon Thin Film Transistors

1990 ◽  
Vol 192 ◽  
Author(s):  
Hiroshi Tsutsu ◽  
Tetsuya Kawamura ◽  
Yutaka Miyata

ABSTRACTEffects of residual phosphorus in the channel region of amorphous silicon thin film transistors(a-Si TFTs) on the TFT characteristics were quantitatively investigated. Concentration and the depth profile of the residual phosphorus were measured by high resolution secondary ion mass spectroscopy(SIMS). The OFF characteristics of a-Si TFTs were also measured.The SIMS data showed that the phosphorus exists about 100nm deep into intrinsic a-Si(i-a-Si), but the OFF characteristics showed that the activity of the residual phosphorus is 4 order of magnitude lower than that of heavily phosphorus doped a-Si(+-a-Si). The residual phosphorus is found to be inactive and stable, and has little effect on a-Si TFT characteristics.These results enabled us to fabricate inverted staggered a-Si TFTs by the simplest process using only 2 photo-mask steps and 1 self-aligned exposure.

1996 ◽  
Vol 424 ◽  
Author(s):  
R. E. I. Schropp ◽  
K. F. Feenstra ◽  
C. H. M. Van Der Werf ◽  
J. Holleman ◽  
H. Meiling

AbstractWe present the first thin film transistors (TFTs) incorporating a low hydrogen content (5 - 9 at.-%) amorphous silicon (a-Si:H) layer deposited by the Hot-Wire Chemical Vapor Deposition (HWCVD) technique. This demonstrates the possibility of utilizing this material in devices. The deposition rate by Hot-Wire CVD is an order of magnitude higher than by Plasma Enhanced CVD. The switching ratio for TFTs based on HWCVD a-Si:H is better than 5 orders of magnitude. The field-effect mobility as determined from the saturation regime of the transfer characteristics is still quite poor. The interface with the gate dielectric needs further optimization. Current crowding effects, however, could be completely eliminated by a H2 plasma treatment of the HW-deposited intrinsic layer. In contrast to the PECVD reference device, the HWCVD device appears to be almost unsensitive to bias voltage stressing. This shows that HW-deposited material might be an approach to much more stable devices.


1996 ◽  
Vol 420 ◽  
Author(s):  
R. E. I. Schropp ◽  
K. F. Feenstra ◽  
C. H. M. Van Der Werf ◽  
J. Holleman ◽  
H. Meiling

AbstractWe present the first thin film transistors (TFTs) incorporating a low hydrogen content (5 - 9 at.-%) amorphous silicon (a-Si:H) layer deposited by the Hot-Wire Chemical Vapor Deposition (HWCVD) technique. This demonstrates the possibility of utilizing this material in devices. The deposition rate by Hot-Wire CVD is an order of magnitude higher than by Plasma Enhanced CVD. The switching ratio for TFTs based on HWCVD a-Si:H is better than 5 orders of magnitude. The field-effect mobility as determined from the saturation regime of the transfer characteristics is still quite poor. The interface with the gate dielectric needs further optimization. Current crowding effects, however, could be completely eliminated by a H2 plasma treatment of the HW-deposited intrinsic layer. In contrast to the PECVD reference device, the HWCVD device appears to be almost unsensitive to bias voltage stressing. This shows that HW-deposited material might be an approach to much more stable devices.


1991 ◽  
Vol 219 ◽  
Author(s):  
K. Kobayashi ◽  
H. Murai ◽  
M. Hayama ◽  
T. Yamazaki

ABSTRACTThe influence of hydrogenation on OFF current of TFTs with a bottom gate staggered structure has been investigated. The hydrogenation is done by exposing the surface of the a-Si:H channel layer to H2 plasma. The hydrogenation decreases the OFF current by more than one order of magnitude. The decrease in the OFF current is attributed to the increase in the density of states at the interface between the a-Si:H channel layer and the SiN passivating layer.


1997 ◽  
Vol 36 (Part 1, No. 10) ◽  
pp. 6226-6229 ◽  
Author(s):  
Huang-Chung Cheng ◽  
Jun-Wei Tsai ◽  
Chun-Yao Huang ◽  
Fang-Chen Luo ◽  
Hsing-Chien Tuan

2009 ◽  
Vol 105 (12) ◽  
pp. 124504 ◽  
Author(s):  
S. L. Rumyantsev ◽  
Sung Hun Jin ◽  
M. S. Shur ◽  
Mun-Soo Park

1989 ◽  
Vol 28 (Part 1, No. 11) ◽  
pp. 2197-2200 ◽  
Author(s):  
Kouichi Hiranaka ◽  
Tetsuzo Yoshimura ◽  
Tadahisa Yamaguchi

1993 ◽  
Vol 297 ◽  
Author(s):  
Byung Chul Ahn ◽  
Jeong Hyun Kim ◽  
Dong Gil Kim ◽  
Byeong Yeon Moon ◽  
Kwang Nam Kim ◽  
...  

The hydrogenation effect was studied in the fabrication of amorphous silicon thin film transistor using APCVD technique. The inverse staggered type a-Si TFTs were fabricated with the deposited a-Si and SiO2 films by the atmospheric pressure (AP) CVD. The field effect mobility of the fabricated a-Si TFT is 0.79 cm2/Vs and threshold voltage is 5.4V after post hydrogenation. These results can be applied to make low cost a-Si TFT array using an in-line APCVD system.


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