| Summary: | 碩士 === 國立中興大學 === 物理學系所 === 102 === Abstract
We investigated the low-frequency noise (LFN) of molybdenum ditelluride (MoTe2) thin film transistors and magnetic tunnel junction (MTJ) field sensors. The W/L ratio of the MoTe2 devices are 4μm/6μm , 10μm /6μm , and 1μm /3μm, respectively. The devices with channel length of 6μm has 5 MoTe2 2D layers, and the device with a channel length of 3μm has 3 layers. We placed the device in a dark vacuum chamber for transport measurements. At small gate-source bias (VGS), the power spectral density (SI) of current increases as source-drain current (IDS) increases. The slope of SI versus IDS log-log plot is about 2 at 1Hz, which complies with Hooge''s Formula. The magnitude difference of Hooge''s parameter (αH) between the devices with 3 layer and 5 layer repectively is about one order. We also compare the magnitude of Hooge''s parameter (αH) of the device operating in p-type and n-type regions; is the difference is found to be about two order of magnitude and the noise amplitude (A) has about one order of magnitude difference. From the dependence of normalized noise power spectral density on the gate-source voltage (VGS), the mobility fluctuation is considered as a dominant LFN mechanism of MoTe2 TFTs for both n-type or p-type operation modes.
We also study the LFN of MTJ field sensors and found the noise amplitude decreases as the resistance increases . In addition, a Lorentzian noise can be observed for a sample with size of 6 μm × 6 μm; the characteristic time of the Lorentzian noise is about 8 Hz.
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