The Instability Characteristics of Amorphous Silicon Thin Film Transistors with Various Interfacial and Bulk Defect States

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
1996 ◽  
Vol 424 ◽  
Author(s):  
Jeong Hyun Kim ◽  
Woong Sik Choi ◽  
Chan Hee Hong ◽  
Hoe Sup Soh

AbstractThe off current behavior of hydrogenated amorphous silicon (a-Si:H) thin film transistors (TFTs) with an atmospheric pressure chemical vapor deposition (APCVD) silicon dioxide (SiO2) gate insulator were investigated at negative gate voltages. The a-Si:H TFT with SiO2 gate insulator has small off currents and large activation energy (Ea) of the off current compared to the a-Si:H TFT with SiNx gate insulator. The holes induced in the channel by negative gate voltage seem to be trapped in the defect states near the a-Si:H/SiO2 interface. The interface state density in the lower half of the band gap of a-Si:H/SiO2 appears to be much higher than that for a-Si:H/SiNx.


1991 ◽  
Vol 219 ◽  
Author(s):  
Norbert Nickel ◽  
Rosari Saleh ◽  
Walther Fuhs ◽  
Helmut Mell

ABSTRACTThin—film transistors (TFTs) were prepared by the glow—discharge deposition of amorphous silicon nitride (a—SiNx:H) and amorphous silicon (a—Si:H). The properties of these TFTs were varied in two ways: a) doping of the amorphous silicon film with phosphine or diborane and b) exposure of the a—SiNx:H film to an oxygen plasma prior to the deposition of the a—Si:H layer. The TFTs are characterized by measurements of the transfer characteristic, ISD(VG) and of the effective density of interface states, Ni(E), using a transient current spectroscopy (TCS). The dependence of Ni(E) on the Fermi—level position in the a—Si:H film suggests that for EC—EF > 0.6eV this quantity is mainly determined by interface related defect states whereas for Ec,—EF <0.6eV it is determined by doping—induced defect states. The exposure to the oxygen plasma results in a reduction of Ni in both the upper and lower half of the gap and in an improvement of the characteristic, in particular in p—channel TFTs. These changes are discussed in terms of the chemical-equilibrium or defect—pool concept.


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.


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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