Study of Germanium nanocrystals in the MOS device with excimer laser annealing
Date Issued
2009
Date
2009
Author(s)
Chen, Jing-Ying
Abstract
In this work, we use germanium nano-crystals (Ge NCs) as a floating gate in silicon dioxide (SiO2) matrix, and then fabricate a MOS capacitor with a tri-layer structure. At First, we use E-gun system to evaporate an ultra-thin Ge layer on SiO2. Then, we use excimer laser annealing system to fabricate Ge NCs. From SEM and AFM images, we ensure that Ge NCs are formed. The size of nano-crystals is dependent on laser power density. We use Lorentz fitting to analyze the Raman spectrum .We use this method to separate the signal of amorphous Ge from that of crystal Ge and investigate the relation between Raman signal intensity and laser power density.rom the capacitance-voltage (C-V), conductance-voltage (G-V), current-voltage (I-V) results, we can investigate the carriers transmission process and charges loss mechanism. For the carriers exchange mechanism, we also propose a single trap model to describe the relation between charge storage characteristics and carrier characteristic time constant. The model is based on SRH theory. C-V, G-V measurement results are used to get trap capacitance, trap conductance and characteristic time constant τ. We utilize our trap model to analyze the relation of biasing voltage, laser power density and traps density.
Subjects
excimer laser
Ge NCs
Raman
hysteresis curve
trap capacitance
trap conductance
Type
thesis
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