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Silicon delta doped layer in phemt

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wmj2011

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I'm doing simulation of phemt using ATLAS SILVACO.
I refer to the HEMT examples database in SILVACO;
why is the delta doped material defined as the same material of the Supply and Spacer layer (AlGaAs) when it should be a Silicon doping layer? why it's not defined as Silicon? Anyone can help me with this? Thanks

Previously, I tried to use the following command to model the Si-doped layer. Is that correct?

doping material=Si gaussian peak=0.0305 n.type conc=2e19 char=10e-4

And for the material layer, I defined th supply, delta doped and spacer layer as the following (I'm using InAlAs):

region num=4 name="Supply" material=InAlAs y.min=0.000 y.max=0.030 x.comp=0.48
region num=5 name="Delta" material=InAlAs y.min=0.030 y.max=0.031 x.comp=0.48
region num=6 name="Spacer" material=InAlAs y.min=0.031 y.max=0.041 x.comp=0.48
 

timof

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Si in your HEMT structure is a doping. Doping atoms are added to the host material (AlGaAs or InAlAs). The concentration o fthe doping atoms are many orders of magnitude (2-3-4-5) lower than the host atom concentration. That's why the material properties of the semiconductor (bandgap, mobility, etc.) are still determined by the host material (these properties may be modified by doping - for example, mobility usually decreases as doping increases), and not by the doping species.

Placing a silicon delta-doped layer into AlGaAs does not make that region silicon. It is silicon-doped AlGaAs.

it is the same situation as when you put boron or arsenic doping to silicon - the semiconductor is still silicon, it does not become boron or arsenic.
 

wmj2011

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Hi timof,

Thanks for giving the Silicon+boron (doping) example.
Now it make sense to me =)
 

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