THE INVESTIGATION OF FREQUENCY AND RADIATION DEPENDENT OF MAIN PHYSICAL PARAMETRES OF Al/SiO2/p-Si (MIS) STRUCTURES


Thesis Type: Postgraduate

Institution Of The Thesis: Gazi University, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2008

Thesis Language: Turkish

Student: İLKE TAŞÇIOĞLU

Consultant: AKİF ÖZBAY

Abstract:

The frequency dependent capacitance-voltage (C-V) and conductance-voltage (G/w-V) characteristics of the Al/SiO2/p-Si (MIS) structures have been investigated by considering series resistance (RS) and interface states (Nss) effects. The C-V and G/w-V measurements of the Al/SiO2/p-Si (MIS) structures were carried out in the frequency range of 500 Hz-5 MHz at room temperature. Experimental results show that both C and G/w of sample decreases with increasing frequency. Such behavior of C and G/w at low frequencies results from the existence of Nss at Si/SiO2 interface. The effect of Rs on the C and G/w are found noticeable at high frequency. Therefore, the high frequencies Cm and Gm/w values measured under both forward and reverse bias were corrected for the effect of Rs to obtain the real Cc and Gc/w of sample. The profile of Rs exhibits an anomalous peak at each frequency about at zero-bias. In addition, the effect of 60Co g-ray exposure on the MIS structures has been investigated using the current-voltage (I-V), C-V and G/w-V characteristics at room temperature. The ideality factor (n) increases with irradiation dose due to an increase radiation induced interface states (Nss). The energy density of Nss distribution profiles as a function Ess-Ev was extracted from the forward bias IV characteristics taking into account the bias dependence of the effective barrier height (e). The values of Nss showing an exponantial decrease with bias from the top of the valance band towards the mid gap. Also, the C-V and G/w-V characteristics of MIS structures show fairly large radiation dispersion. The Rs profile of MIS structures was extracted from the Cm and Gm/w measurements according to admittance method and its value increases with increasing dose. Experimental results show that the insulator layer between metal and semiconductor g-radiation play an important role in the electrical parameters such as ideality factor, barrier height and interface states (Nss).