Calculation from the currentvoltage and capacitancevoltage measurements of characteristics parameters of Cd/CdS/n-Si/Au-Sb structure with CdS interface layer grown on n-Si substrate by SILAR method
The CdS thin film has been directly formed on n-type Si substrate to form an interfacial layer between cadmium (Cd) and n-type Si with Successive Ionic Layer Adsorption and Reaction (SILAR) method. An AuSb electrode has been used as an ohmic contact. The Cd/CdS/n-Si/AuSb structure has demonstrated clearly rectifying behaviour by the currentvoltage (IV) curves studied at room temperature. The characteristics parameters such as barrier height, ideality factor and series resistance of Cd/CdS/n-Si/AuSb structure have been calculated from the forward bias IV and reverse bias C?2V characteristics. The diode ideality factor and the barrier height have been calculated as n=2.06 and ?b=0.92eV by applying a thermionic emission theory, respectively. The diode shows non-ideal IV behaviour with an ideality factor greater than unity that can be ascribed to the interfacial layer, the interface states and the series resistance. At high current densities in the forward direction, the series resistance (Rs) effect has been observed. The values of Rs obtained from dV/d(lnI)I and H(I)I plots are near to each others (Rs =182.24? and Rs =186.04?, respectively). This case shows the consistency of the Cheung?s approach. In the same way, the barrier height calculated from C?2 -V characteristics varied from 0.698 to 0.743eV. Furthermore, the density distribution of interface states (Nss) of the device has been obtained from the forward bias IV characteristics. It has been seen that, the Nss has almost an exponential rise with bias from the mid gap toward the bottom of conduction band.
cds silar method interface states mis structure schottky diode