Factors influencing the varaiation of depletion capacitance of MOS capacitor

[KITTU123]

Hi , i am interested to know physics behind MOS capacitors, on which iam currently working in . i started to fabriacate a MOS capacitor without using oxide (silicon dioxide) layer, i have read in articles that a MOS capacitor can be fabricated by using the native oxide layer ( naturally formed ) as an insulator in between the metal contact and semiconductor.i observe a relevant results (similar to MOS capacitor). but i observe that there is no stable characteristics in cv measurents from one sample to other sample.i.e especially near the depletion mode of operation the curve are approaching both towards negative direction of voltage of certain sample and the curves of other sample are approaching in positive direction of voltage.which is undesirable. can i know the reasons affecting the instability in these characteristics and methods to get a stable behaviour. please suggest me the topics along with a good book to be read , in order to understand the physics behind this.

 

[hasib_eee]

Hello. You have to go through the detail of a PN junction first. Then a P+n junction. A MOS capacitor in depletion mode is almost like a P+n or N+p junction. P+ or N+ means that part is heavily doped.

MOS capacitor CV curve depends on many parameters, like oxide thickness,substrate doping, fixed oxide charge,interface trap charge, frequency of CV measurement.

S.M.SZE's book about device physics has a wonderful chapter about MIS capacitor. You can refer to that for better understanding.

Best Regards.

M.Satter.