Title :
Study of instabilities in amorphous-silicon thin-film transistors by transient current spectroscopy
Author :
Nickel, Norbert ; Fuhs, Walther ; Mell, Helmut
Author_Institution :
Fachbereich Phys., Marburg Univ., West Germany
fDate :
1/1/1990 12:00:00 AM
Abstract :
A study of the metastable changes in a-Si:H/a-SiN:H thin-film transistors (TFTs) caused by prolonged application of high gate voltages by photoinduced discharge (PID) measurements and transient current spectroscopy (TCS) is discussed. Two effects can be distinguished: (1) a pronounced shift of the flatband voltage, which is caused by charge trapping in the dielectric, and (2) the creation of metastable states in the accumulation layer. It is found that PID is unable to detect changes of the density of defect states near the interface Ni. TCS, on the other hand, reveals that voltage stress causes an increase of Ni by up to a factor of 2. The temperature dependence of this effect indicates an activation energy for defect formation of approximately 0.7 eV
Keywords :
amorphous semiconductors; electron traps; hydrogen; silicon; silicon compounds; thin film transistors; 0.7 eV; accumulation layer; amorphous Si:H-SiN:H thin film transistor; charge trapping; defect formation activation energy; defect state density; flatband voltage shift; high gate voltages; metastable changes; photoinduced discharge; temperature dependence; transient current spectroscopy; voltage stress; Current measurement; Degradation; Metastasis; Neodymium; Nickel; Partial discharges; Spectroscopy; Stress; Thin film transistors; Threshold voltage;
Journal_Title :
Electron Devices, IEEE Transactions on
