p-Si/DNA photoconductive diode for optical sensor applications

The junction parameters of Al/p-Si/Ag and Al/p-Si/DNA/Ag diodes were studied using current-voltage (I-V), capacitance-voltage (C-V), and capacitance-frequency (C-f) measurements. The photoresponse properties of the diodes were analyzed using transient photocurrent measurements. The photoresponse of the Al/p-Si/DNA/Ag diode is better than that of Al/p-Si/Ag diode. The ideality factor and barrier height values of the Al/p-Si/DNA/Ag diode were obtained to be 1.2 +/- 0.1 and 0.56 +/- 0.02 eV, respectively. The capacitance of the diodes increases with decreasing frequency which is explained by the change in the interface states. These results indicate that the p-Si/DNA junction could be used as an optical sensor. (C) 2011 Elsevier B.V. All rights reserved.