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# System prepended metadata

title: Semiconductor_Mos Capator

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# Semiconductor_Mos Capator
* # Three cases at semiconductor surface

### When I=0, dE/dx =0,i.e.,Fermi level is flat:

| Accumulation case |Depletion case| Inversion case  |
| -------------- | -------------- | ----------------- |
|        ![](https://i.imgur.com/G7hlvcb.png)|![](https://i.imgur.com/iRTw2BG.png)|![](https://i.imgur.com/XmupWXe.png)|
| ![](https://i.imgur.com/1HUU3hN.png)|     ![](https://i.imgur.com/iCJneHS.png)| ![](https://i.imgur.com/9nrAjc0.png)|


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* # Surface Depletion Region

* ### The figure shows the energy band diagram at surface of a p-type semiconductor.

 ![](https://i.imgur.com/FRpVIlI.png)
 ![](https://i.imgur.com/JDf62Zh.png)
 ![](https://i.imgur.com/XDTQ7s3.png)
 
 
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* # Charge in the semicinductir versus applied voltage
![](https://i.imgur.com/qkZo2n9.png)
![](https://i.imgur.com/0P3eKhX.png)


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* # Maximum depletion width
![](https://i.imgur.com/D1KXGQI.png)
![](https://i.imgur.com/VKWjW2j.png)

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* # Ideal MOS curve
![](https://i.imgur.com/Z2SzPpJ.png)
![](https://i.imgur.com/t2GAyn1.png)
![](https://i.imgur.com/MrwMRqD.png)
![](https://i.imgur.com/pksZzCa.png)
![](https://i.imgur.com/ARCoAwg.png)
![](https://i.imgur.com/KNpQFlp.png)
![](https://i.imgur.com/JWZPlRj.png)

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* # SiO2-Si MOS capacitor
![](https://i.imgur.com/U9GS0hc.png)
![](https://i.imgur.com/4FJ5H63.png)
![](https://i.imgur.com/Nd41GE6.png)
![](https://i.imgur.com/Z0VPB1p.png)
![](https://i.imgur.com/Kd220Qm.png)
![](https://i.imgur.com/0dHlzQv.png)
![](https://i.imgur.com/QeTEH2Y.png)
![](https://i.imgur.com/1iwfz2W.png)
![](https://i.imgur.com/SxEAzEr.png)

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# Summary Of MOS Capacitor

* ### At the SiO2 interface, there are "3 possible charge distribution":


| Accumulation|Depletion| Inversion |
| -------------- | -------------- | ----------------- |
|        ![](https://i.imgur.com/G7hlvcb.png)|![](https://i.imgur.com/iRTw2BG.png)|![](https://i.imgur.com/XmupWXe.png)|

### The inversion is most important distribution, because it relates to the conducting channel for MOSFET operation.

* ### We have considered the characteristics of an ideal MOS capacitor. For a practical silicon MOS capacitor,the work function difference is generally not zero and there are various charges in the oxide or at the SiO2-Si interface that will affect the ideal MOS characteristics.

* ### Tunneling is the most important conduction process in SiO2. Tunneling current will generate defects in SiO2.When defects become dense enugh to form a continuous chain connecting the gate to the channel, catastrophic breakdown will occur.