Abstract
Low-frequency noises in GaAs MESFET are usually observed when investigating the drain current and substrate leakage current under sidegate bias conditions. Experimental results show that the magnitude of low-frequency noises is in a direct dependency upon the sidegate bias and the noises in drain current will disappear if sidegate bias increases more negatively beyond a certain voltage. A mechanism associated with the substrate conductivity and the channel-substrate junction modulated by sidegate bias is proposed to explain the fluctuation of low-frequency noises.
Highlights
Low-frequency noises in GaAs MESFET are usually observed when investigating the drain current and substrate leakage current under sidegate bias conditions
Based on the experimental results presented above, we propose that the substrate conductivity and channel-substrate junction which are modulated by the sidegating voltage take full responsibility for the low-frequency noises (LFN) in currents of GaAs MESFET
From the analysis shown above, resistance of SI substrate (Rsub) varies with VSG, the voltage drops across the C-S junction changes correspondingly
Summary
Low-frequency noises in GaAs MESFET are usually observed when investigating the drain current and substrate leakage current under sidegate bias conditions. A mechanism associated with the substrate conductivity and the channel-substrate junction modulated by sidegate bias is proposed to explain the fluctuation of low-frequency noises. While Wager pointed out that LFN in channel current could not be attributed to the oscillations in leakage current of the substrate, but related to the peculiarities of channel-substrate junction [9]. LFN in MESFET’s currents is investigated under sidegating conditions, and the mechanism is identified whereby the current fluctuation is directly related to the sidegate bias. Unlike Birbas’s explanation in terms of an unreal negative capacitance of the depletion region in buffer-channel interface [11], we associate LFN with the substrate conductivity and channel-substrate junction modulated by sidegate bias.
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